First reef tank, extreme tank downturn. No idea what to do. Appreciate help!

[liddojunior]

I come from freshwater fishkeeping. And always wanted to give coral reef tanks a try. I read guides and watch videos on how to set up a reef tank. Every coral purchased with research done before hand for best results. I started with corals that are listed as easy to keep. Mainly soft corals. For lps I got favia and an acan to try them out. I then moved on to adding a Torch after it grew 2 new heads, I decided to go for a garden (expensive to buy). The tank for a while has been going great then it took a sudden downturn and have had massive coral lost. I'm on my last few corals and my BTA is barely hanging on to life. I really am lost on what is wrong and what I need to do to rescue all the inverts.

I first had a sizable growing Euphyllia garden die suddenly turning into brown mush overnight (at the time my Mg was 1380 ppm) and then a big algae outbreak happened and then lost a ton of corals (Including GSP, Xenia, Kenya trees, cloves, some zoas). All my corals before hand were growing, had see them double in size. So it is really disheartening to see everything turn to mush. I didn't have any problem algae before, I would get some brown algae on the glass and would just scrape it once a week.

Right now all my corals seem to be getting coated in this hard to remove algae. Dipping in CoralRX doesn't' seem to remove the algae and if I use peroxide outside of the tank, it removes it but then it just grows back during the night.

The only corals I have left are 3 mushrooms, couple frags of zoas, and 3 leather frags, and a small bit of pulsing xenia. None of the polyps are extending, and have gotten smaller in size)
The fish, hermit and snails don't seem to be bothered by anything. The only corals that aren't bothered at all are my Duncan corals.
I've had this problem for over a month now and really need advice

Things I have done

Stopped skimmer (Nitrates went down to 0 then had dino explosion show up after Euphyllia all died)​

I took out the corals and brushed and scraped algae and slime of the rocks and walls​

I tried dipping corals​

I've checked for pest​

Serial water changes (Over a week 100% of water has been changed)​

Kept testing parameters (Nitrate and phosphate have gone back up, and have been stable for 2 weeks)​

Add some extra carbon since the leathers were all shedding​

Stopped dosing amino acids and All in reef (Ca, kH, Mg [kH is high so read I should stop dosing])​

Things I do dose​

Live phyto​

Microbacterclean​

(No weird airborne contaminates, its in my fish room and don't use any chemicals to clean around)​

​

Tank equipment (Set up in February and first corals were in August)

Waterbox Cube 10​

Tunze 9001 skimmer​

Hydor Nano wavemaker​

Morning: Wave mode, Intermediate frequency, 100% intensity​

Daytime: Random flow​

Night: Wave mode, Low frequency, 40% intensity​

JBL Nano ATO (5 gallon RO water reservoir)​

50 watt Fluval Heater​

Sicce return pump​

15 lbs live rock​

3 in sand bed​

Kessil A80 Tune Blue (Set towards blue, 100% intensity 12 hr time control)​

Media​

Seachem matrix (1 liter)​

Seachem purigen​

Filter floss pads​

Carbon pad (one small one replaced monthly)​

Doing weekly 10% water changes​

Don't mix my water, use LFS natural seawater (I can see the ocean from my bedroom)​

​

Tank occupants

2 juvinelle O. Clownfish​

1 neon goby​

Peppermint shrimp​

2 blue legged hermit crabs​

Assorted snails (Nerite [3], Cherith[3], Nassarius[3], Margarita[3], astrea [3], trochus[1])​

Several bristle starfish​

Pods (I had used ecopods from algaebarn)​

​

Parameters (Test kits: Red sea, salifort, hanna)

Temp: ~27-27.5 C (Hanna)​

Salinity: 1.024 SG (Hanna)​

Ammonia & Nitrite: 0 ppm​

Nitrate: 5 ppm​

Phosphate: Less than 0.03 ppm​

pH: 8.2​

Ca: 410 ppm (Red Sea)​

kH: 10.9 (Red Sea)​

Mg: 1200 ppm (Red Sea)​

​

 

[Reef Psychology]

It’s times like these that you have to be very methodical and not panic, changing things too rapidly and without knowing what the cause is can create a cascade of issues.

Unplug and examine your heater very carefully for cracks or a short. Use something like Poly pads to deal with impurities/chemicals in the water. Check your RODI. Buy another small batch of salt to eliminate the possibility of contamination. Did you use any cleaners near the aquarium? Check the rear chambers for dead stuff or for anything that might have fallen back there. Setup a QT tank of 5-10 gallons with a cheap in tank filter and Stability bacteria just in case you have to move the animals. Leave the lights off for 24 hours to see what happens to the algae.

 

[liddojunior]

It’s times like these that you have to be very methodical and not panic, changing things too rapidly and without knowing what the cause is can create a cascade of issues.

Unplug and examine your heater very carefully for cracks or a short. Use something like Poly pads to deal with impurities/chemicals in the water. Check your RODI. Buy another small batch of salt to eliminate the possibility of contamination. Did you use any cleaners near the aquarium? Check the rear chambers for dead stuff or for anything that might have fallen back there. Setup a QT tank of 5-10 gallons with a cheap in tank filter and Stability bacteria just in case you have to move the animals. Leave the lights off for 24 hours to see what happens to the algae.

Thanks for the reply.
The heater is good and I’ve replaced it in case. No cleaners used near of course. I checked the back for anything, didn’t find anything but some settled sand (probably from when it was first set up).

RODI not sure how to check, I buy mine from LFS. But could get milli q water.

I’ve never heard of poly pads, I ordered some! Thanks for that recommendation.

 

[Tamberav]

Was alk always a steady number? If so, what was it before? What were all the parameters before the euphyallia died?

Were you dosing all4reef based on consumption?

I have found they can be sensitive to alk spikes, low nutrients, or rapid changes in nutrients.

Brown jelly also effects Euphyllia but I find this is sort of a slower death... one or two start to turn to brown goo and then slowly other colonies become effected, etc.

I would say their massive death potentially set off the algae/other problems.

 

[liddojunior]

Was alk always a steady number? If so, what was it before? What were all the parameters before the euphyallia died?

Were you dosing all4reef based on consumption?

I have found they can be sensitive to alk spikes, low nutrients, or rapid changes in nutrients.

Brown jelly also effects Euphyllia but I find this is sort of a slower death... one or two start to turn to brown goo and then slowly other colonies become effected, etc.

I would say their massive death potentially set off the algae/other problems.

The Alk was about the same before that it was at 10.7 and Ca was 440
So they have gone done a bit from when I stoped dosing. I basically was dosing based on the instructions and using test kits to measure it wasn’t changing. The reason I was dosing was just to get Mg higher from the salt water I was buying that was more around 1200 ppm. And dosed during water changes. I was testing more biweekly, I don’t really know how to change parameters so was mostly testing to check nothing looked grossly wrong.

I would say nutrients seemed to have gone down before hand, so nutrients might have been too low at the time

 

[14 foot reef]

Did I miss in this discussion length of time tank has been set up ?
And what was the time frame of adding all the corals?

 

[Dom]

Doing weekly 10% water changes​

Don't mix my water, use LFS natural seawater (I can see the ocean from my bedroom)​

​

Parameters (Test kits: Red sea, salifort, hanna)

Temp: ~27-27.5 C (Hanna)​

Salinity: 1.024 SG (Hanna)​

Ammonia & Nitrite: 0 ppm​

Nitrate: 5 ppm​

Phosphate: Less than 0.03 ppm​

pH: 8.2​

Ca: 410 ppm (Red Sea)​

kH: 10.9 (Red Sea)​

Mg: 1200 ppm (Red Sea)​

General rule of thumb is that water changes should be faithful at 20% weekly. But you may vary this based on need ( rate of element consumption and nutrient levels ).

You never know what you are getting when you buy water. I would suggest making your own using RODI water.

- Your temperature range is running 80-81.5 and a bit warm. I target 76-77 degrees.
- Your salinity is a bit low. I target 1.026.
- Nitrates are pretty low; I find my corals do better with elevated Nitrates.
- Calcium is good.
- Alk is a bit high; I target 8-8.5
- Magnesium is ok, although, mine runs in the 1400-1450 range.

I'd be interested in seeing a full tank shot as a lot can be gleaned from observation.

I would also like to know what lighting you use and the dimensions of the tank. This is important as you need to do more than light the tank, you need to light the tank with ample penetration.

Also, are you using power heads? Flow is very important and should be chaotic in nature. It is common for people to place power heads so they face in the same direction. Power heads should be pointed at each other to make the flow more random.

 

[Lavey29]

You will be dealing with ugly stages throughout the first year so not unusual here. Torches are finicky difficult euphyllia to sustain in new tanks. Your parameters are off. You want nitrates at 10 and phosphate at .05 to .1. Get magnesium to 1500, it helps get rid of algae.

Weekly water changes with manual removal and siphoning. Cut light to 6 hours with blue and uv only. No whites. Maintain diverse cleaner crew. If BJD is suspected then remove infected coral. Coral RX only treats for pest bugs. Dose phytoplankton daily and add some more Pods. Dose beneficial bacteria like PNS probio weekly.

 

[threebuoys]

Sounds like you are methodically considering all the variables you can think of.

A 10 gallon aquarium can be challenging to maintain stability. A couple of drops of H2o2 or some other chemical can quickly and unexpectedly change the balance while in a larger tank it would go unnoticed. Hope you are able to get to the bottom of it.

 

[liddojunior]

General rule of thumb is that water changes should be faithful at 20% weekly. But you may vary this based on need ( rate of element consumption and nutrient levels ).

You never know what you are getting when you buy water. I would suggest making your own using RODI water.

- Your temperature range is running 80-81.5 and a bit warm. I target 76-77 degrees.
- Your salinity is a bit low. I target 1.026.
- Nitrates are pretty low; I find my corals do better with elevated Nitrates.
- Calcium is good.
- Alk is a bit high; I target 8-8.5
- Magnesium is ok, although, mine runs in the 1400-1450 range.

I'd be interested in seeing a full tank shot as a lot can be gleaned from observation.

I would also like to know what lighting you use and the dimensions of the tank. This is important as you need to do more than light the tank, you need to light the tank with ample penetration.

Also, are you using power heads? Flow is very important and should be chaotic in nature. It is common for people to place power heads so they face in the same direction. Power heads should be pointed at each other to make the flow more random.

My heater is set to 78 but it goes up to 80 probably because the pumps and light.

For salinity that the parameter I feel most worried about changing, I could let it evaporate slowly to get it to 1.026.

For Alk, not sure how to change this. I don’t dose it and I’ve done water changes. Was expecting it to drop but it always seems to be around 10. The saltwater I buy seems to be around that much.

The light I use is Kessil A80. The wavemaker I have is set to clash into the power head flow. It’s a 10 gallon so just have the one power head that intersects the return flow.

Did I miss in this discussion length of time tank has been set up ?
And what was the time frame of adding all the corals?

Says in post. Set up early this year and late summer and fall was time frame of corals. Once a month I would add about a handful of frags.

You will be dealing with ugly stages throughout the first year so not unusual here. Torches are finicky difficult euphyllia to sustain in new tanks. Your parameters are off. You want nitrates at 10 and phosphate at .05 to .1. Get magnesium to 1500, it helps get rid of algae.

Weekly water changes with manual removal and siphoning. Cut light to 6 hours with blue and uv only. No whites. Maintain diverse cleaner crew. If BJD is suspected then remove infected coral. Coral RX only treats for pest bugs. Dose phytoplankton daily and add some more Pods. Dose beneficial bacteria like PNS probio weekly.

I’ll increase mag slowly in that case. I’ll keep dosing phyto.

 

[Lavey29]

My heater is set to 78 but it goes up to 80 probably because the pumps and light.

For salinity that the parameter I feel most worried about changing, I could let it evaporate slowly to get it to 1.026.

For Alk, not sure how to change this. I don’t dose it and I’ve done water changes. Was expecting it to drop but it always seems to be around 10. The saltwater I buy seems to be around that much.

The light I use is Kessil A80. The wavemaker I have is set to clash into the power head flow. It’s a 10 gallon so just have the one power head that intersects the return flow.



Says in post. Set up early this year and late summer and fall was time frame of corals. Once a month I would add about a handful of frags.



I’ll increase mag slowly in that case. I’ll keep dosing phyto.

Bring nitrates and phosphate to proper parameters or your remaining corals will starve

 

[threebuoys]

In your first post, you described your lost as sudden. Just how quickly was "sudden"?

I ask because many of the comments seem to focus on what needs to happen for long term stability and success. A lot of food for thought. On the other hand, if sudden was over a period of just a couple of days, I would be concerned something more critical than stable parameters might be the culprit.

 

[liddojunior]

Bring nitrates and phosphate to proper parameters or your remaining corals will starve

what would be proper? I’m worried about increasing this without causing ammonia issues

 

[Lavey29]

what would be proper? I’m worried about increasing this without causing ammonia issues

LPS corals need nutrients. Nitrates 10 and phosphate. 05 to .1. The lack of nutrients is probably what triggered your euphyllia downfall. Corals can be struggling on the inside for weeks or months before all of a sudden one day, bam...the outward signs of stress and malnutrition appear and then rapid decline. A nano tank like yours needs weekly small water changes. Feed the fish more to bring up nutrients or dose neophos and neonitro which is what I had to do.

 

[I never finish anythi]

Best method is make the water you're self . I would honestly start there . You don't know what the heck is in natural sea water in my opinion. It can change on so many levels. Not worth the risk

 

[liddojunior]

In your first post, you described your lost as sudden. Just how quickly was "sudden"?

I ask because many of the comments seem to focus on what needs to happen for long term stability and success. A lot of food for thought. On the other hand, if sudden was over a period of just a couple of days, I would be concerned something more critical than stable parameters might be the culprit.

Good question. So to make it a clear timeline.

3 weeks ago
I added some new corals I bought from tidal gardens. One was kinda DOA. Its tissue was bubbling and warted. And the bag water was brown and cloudy. I emailed them got a refund and was told I should still place in tank and the leftover half would recover. It turned to brown mush after 3 days. (So dont know if this detail matters not sure if corals can bring in like a viral disease? I just read online that soft corals dont ship well and it could have just been DOA from shipping)
Then I started to notice the Euphyllia started to be more retract. So I emailed a LFS asking for thoughts, and was recommended I dose Mg to get it to 1400-1450. I bought just magnesium cause the all in reef is all 3 parameters. (I never got to dosing it). Nitrates were at 2.5 ppm and Phos greater than 0 but barely.

2 weeks ago
All the Euphyllia died overnight. By dead I mean half the heads were literally half brown mush and some were empty skeletons. They smelled SUPER sweet. I then did a 2 serial 25% water changes. And removed the Euphyllia. Tested parameters, at home and at the LFS. Nitrates peaked at 10 ppm and Phos 0.2. But after water changes went to around Nitrates 5 ppm and Phos 0.1.

1.5 weeks ago
Huge algae outbreak. It was bubbling snot everywhere. I scrapped it as I could and using filter floss to catch it and then toss the algae caught in it. I noticed all the corals had their polyps closed and I assumed they were bothered by the nets of snotty like algae. Nitrates were at 0ppm and Phos were 0. I assume the algae just used all those nutrients.
I took out the corals did a dip and then use soft brush to brush off the snot. (Used 3% peroxide diluted in tank water to brush off algae.) Placed in clean new saltwater then moved back to the tank with a 25% water changed.

1 week ago
The algae is still there but not awful. And zoas started to open up. My acan was open. But my rhodactis mushroom had a gaping mouth and my BTA went from a small little plump guy into a retracted nub. And the xenia corals got really skinny. Nitrates were at 2.5ppm and Phos were less than 0.03 but not 0.
And it looked like the leathers were shiny, I assumed they were ready to start shedding. They were firm but have this dark coating on them.

Then I woke up to kenya tree all gone, sympodium gone, cloves half gone, sea fan gone (left a wire skeleton?). Waving xenia gone, GSP gone, it was actually filling the water with green pigments as it was kinda disintegrating. Favia turned into mush.

Its been a week and no coral looks good expect for the duncans.

I panic, and start to think what could go wrong. Tested water parameters. Still similar. I then did a series of water changes and have changed out over 100% of the water. And currently have lost a few zoa heads but they have yet to open, and seem to be getting this slime algae growing on them.

I honestly want to try a different source of saltwater but feel like changing saltwater source is like a huge no no. Basically I don't know what is wrong and just trying to be as detailed as I can so someone could help.


Added photos I had from Nov 24th ! I have since moved the green crown leather to be more in a flow area to help with shedding and moved the duncans as well to where the Euphyllia area just cause had space on that rock now.

 

[liddojunior]

General rule of thumb is that water changes should be faithful at 20% weekly. But you may vary this based on need ( rate of element consumption and nutrient levels ).

You never know what you are getting when you buy water. I would suggest making your own using RODI water.

- Your temperature range is running 80-81.5 and a bit warm. I target 76-77 degrees.
- Your salinity is a bit low. I target 1.026.
- Nitrates are pretty low; I find my corals do better with elevated Nitrates.
- Calcium is good.
- Alk is a bit high; I target 8-8.5
- Magnesium is ok, although, mine runs in the 1400-1450 range.

I'd be interested in seeing a full tank shot as a lot can be gleaned from observation.

I would also like to know what lighting you use and the dimensions of the tank. This is important as you need to do more than light the tank, you need to light the tank with ample penetration.

Also, are you using power heads? Flow is very important and should be chaotic in nature. It is common for people to place power heads so they face in the same direction. Power heads should be pointed at each other to make the flow more random.

Here is todays full tank shot

 

[Dom]

Here is todays full tank shot

Sorry, when I said full tank shot, I meant a picture that included the whole tank, so we can see your filtration, lighting and flow supplement.

From what I can see, your return pump is the sole source of flow in the tank. The device in the top right corner... is that a power head or is that a glass cleaner? I'm thinking glass cleaner as you wouldn't install a powerhead on the front of the tank.

I can't see which lighting you're using. Please tell us.

Also, your tank depth is important. it will help us to determine if your light is penetrating the water with enough intensity to support coral growth.

 

[Lavey29]

Good question. So to make it a clear timeline.

3 weeks ago
I added some new corals I bought from tidal gardens. One was kinda DOA. Its tissue was bubbling and warted. And the bag water was brown and cloudy. I emailed them got a refund and was told I should still place in tank and the leftover half would recover. It turned to brown mush after 3 days. (So dont know if this detail matters not sure if corals can bring in like a viral disease? I just read online that soft corals dont ship well and it could have just been DOA from shipping)
Then I started to notice the Euphyllia started to be more retract. So I emailed a LFS asking for thoughts, and was recommended I dose Mg to get it to 1400-1450. I bought just magnesium cause the all in reef is all 3 parameters. (I never got to dosing it). Nitrates were at 2.5 ppm and Phos greater than 0 but barely.

2 weeks ago
All the Euphyllia died overnight. By dead I mean half the heads were literally half brown mush and some were empty skeletons. They smelled SUPER sweet. I then did a 2 serial 25% water changes. And removed the Euphyllia. Tested parameters, at home and at the LFS. Nitrates peaked at 10 ppm and Phos 0.2. But after water changes went to around Nitrates 5 ppm and Phos 0.1.

1.5 weeks ago
Huge algae outbreak. It was bubbling snot everywhere. I scrapped it as I could and using filter floss to catch it and then toss the algae caught in it. I noticed all the corals had their polyps closed and I assumed they were bothered by the nets of snotty like algae. Nitrates were at 0ppm and Phos were 0. I assume the algae just used all those nutrients.
I took out the corals did a dip and then use soft brush to brush off the snot. (Used 3% peroxide diluted in tank water to brush off algae.) Placed in clean new saltwater then moved back to the tank with a 25% water changed.

1 week ago
The algae is still there but not awful. And zoas started to open up. My acan was open. But my rhodactis mushroom had a gaping mouth and my BTA went from a small little plump guy into a retracted nub. And the xenia corals got really skinny. Nitrates were at 2.5ppm and Phos were less than 0.03 but not 0.
And it looked like the leathers were shiny, I assumed they were ready to start shedding. They were firm but have this dark coating on them.

Then I woke up to kenya tree all gone, sympodium gone, cloves half gone, sea fan gone (left a wire skeleton?). Waving xenia gone, GSP gone, it was actually filling the water with green pigments as it was kinda disintegrating. Favia turned into mush.

Its been a week and no coral looks good expect for the duncans.

I panic, and start to think what could go wrong. Tested water parameters. Still similar. I then did a series of water changes and have changed out over 100% of the water. And currently have lost a few zoa heads but they have yet to open, and seem to be getting this slime algae growing on them.

I honestly want to try a different source of saltwater but feel like changing saltwater source is like a huge no no. Basically I don't know what is wrong and just trying to be as detailed as I can so someone could help.


Added photos I had from Nov 24th ! I have since moved the green crown leather to be more in a flow area to help with shedding and moved the duncans as well to where the Euphyllia area just cause had space on that rock now.

Having corals die rapidly with brown jelly substance and odor is BJD. This occurs when corals are under stress and their immune systems collapse. Heads die very quickly overnight.

Brown snotty algae is dinos which occurs when nitrates and phosphate are bottomed out as you stated in your post in the sequence timeliness.

The obvious main issue here is the instability of your parameters which is typical for new tanks under a year old. You need to stick to basic nano tank care and focus on stabilizing your parameters in proper ranges.

As the other poster mentioned get an RODI and make your own salt water. It's easy.

 

[vetteguy53081]

I come from freshwater fishkeeping. And always wanted to give coral reef tanks a try. I read guides and watch videos on how to set up a reef tank. Every coral purchased with research done before hand for best results. I started with corals that are listed as easy to keep. Mainly soft corals. For lps I got favia and an acan to try them out. I then moved on to adding a Torch after it grew 2 new heads, I decided to go for a garden (expensive to buy). The tank for a while has been going great then it took a sudden downturn and have had massive coral lost. I'm on my last few corals and my BTA is barely hanging on to life. I really am lost on what is wrong and what I need to do to rescue all the inverts.

I first had a sizable growing Euphyllia garden die suddenly turning into brown mush overnight (at the time my Mg was 1380 ppm) and then a big algae outbreak happened and then lost a ton of corals (Including GSP, Xenia, Kenya trees, cloves, some zoas). All my corals before hand were growing, had see them double in size. So it is really disheartening to see everything turn to mush. I didn't have any problem algae before, I would get some brown algae on the glass and would just scrape it once a week.

Right now all my corals seem to be getting coated in this hard to remove algae. Dipping in CoralRX doesn't' seem to remove the algae and if I use peroxide outside of the tank, it removes it but then it just grows back during the night.

The only corals I have left are 3 mushrooms, couple frags of zoas, and 3 leather frags, and a small bit of pulsing xenia. None of the polyps are extending, and have gotten smaller in size)
The fish, hermit and snails don't seem to be bothered by anything. The only corals that aren't bothered at all are my Duncan corals.
I've had this problem for over a month now and really need advice

Things I have done

Stopped skimmer (Nitrates went down to 0 then had dino explosion show up after Euphyllia all died)​

I took out the corals and brushed and scraped algae and slime of the rocks and walls​

I tried dipping corals​

I've checked for pest​

Serial water changes (Over a week 100% of water has been changed)​

Kept testing parameters (Nitrate and phosphate have gone back up, and have been stable for 2 weeks)​

Add some extra carbon since the leathers were all shedding​

Stopped dosing amino acids and All in reef (Ca, kH, Mg [kH is high so read I should stop dosing])​

Things I do dose​

Live phyto​

Microbacterclean​

(No weird airborne contaminates, its in my fish room and don't use any chemicals to clean around)​

​

Tank equipment (Set up in February and first corals were in August)

Waterbox Cube 10​

Tunze 9001 skimmer​

Hydor Nano wavemaker​

Morning: Wave mode, Intermediate frequency, 100% intensity​

Daytime: Random flow​

Night: Wave mode, Low frequency, 40% intensity​

JBL Nano ATO (5 gallon RO water reservoir)​

50 watt Fluval Heater​

Sicce return pump​

15 lbs live rock​

3 in sand bed​

Kessil A80 Tune Blue (Set towards blue, 100% intensity 12 hr time control)​

Media​

Seachem matrix (1 liter)​

Seachem purigen​

Filter floss pads​

Carbon pad (one small one replaced monthly)​

Doing weekly 10% water changes​

Don't mix my water, use LFS natural seawater (I can see the ocean from my bedroom)​

​

Tank occupants

2 juvinelle O. Clownfish​

1 neon goby​

Peppermint shrimp​

2 blue legged hermit crabs​

Assorted snails (Nerite [3], Cherith[3], Nassarius[3], Margarita[3], astrea [3], trochus[1])​

Several bristle starfish​

Pods (I had used ecopods from algaebarn)​

​

Parameters (Test kits: Red sea, salifort, hanna)

Temp: ~27-27.5 C (Hanna)​

Salinity: 1.024 SG (Hanna)​

Ammonia & Nitrite: 0 ppm​

Nitrate: 5 ppm​

Phosphate: Less than 0.03 ppm​

pH: 8.2​

Ca: 410 ppm (Red Sea)​

kH: 10.9 (Red Sea)​

Mg: 1200 ppm (Red Sea)​

​

While algae is a good sign of nutrients. . . It comes to what level of nutrients
What is your phosphate-nitrate-ph and salinity levels?
What test kit are you using?
Have you used tap water from faucet at some point or RODI water ?
Zoas may be affected by bright light, inadequate flow and high Phosphate levels.

Verify your nitrate and phos levels, lower amount of food fed and reduce while light intensity.
Assure to have cleaner snails (not just one or two) such as : Astrea, Turbo grazer, cerith, trochus and nassarius.
Also about 8-10 caribbean blue leg hermit crabs and even a pencil usrchin