Diatom problem-please help, I’m absolutely stumped

[candelloro]

Ok so let me begin

I started a 2.5 G reef back in May 26 and I currently still have it running with two hermits and corals that are all doing fine.

Around June 20, I noticed a huge diatom bloom in my tank and so far I’ve lost 3 small fish (not all at once in the same tank). Lost a neon goby not even 2 hours after putting him into the tank on Monday.

Now recently the diatoms are almost all gone on the rocks and the ones on the glass are dying down as well. I’ve noticed some flat green algae starting to grow on the rocks now. My question is, do diatoms deplete oxygen in the water? Every time I added a new fish, they’d breathe fast. I run a carbon filter along with a sponge as well. I also have a plastic top on the tank that only has one feeding hole as the opening, and I run a koralia 240 nano powerhead for water circulation, could the lid be trapping oxygen as well?

Parameters are spot on so I don’t think it’s my water quality, should I wait until the diatoms are all gone before adding any new fish? Let me know what you guys think, I feel absolutely devastated and disappointed in myself for losing so many fish in a short amount of time. (Again I didn’t have 3 fish in this small of a tank all at the same time.)

Ammonia-0
Nitrite-0
Nitrate-10 ppm
pH-8.2

 

[Hemmdog]

Salinity and temp?

 

[Craigdoc]

Sorry for your loss mate, diatoms won't kill the fish, the best way to remove them is syphoning them out when doing water changes and making sure your RO water is of good quality, they tend to feed on silicates so once they've consumed all the silicates available they'll die back which is what sounds like is happening.

If you don't have a skimmer then good surface agitation is essential for gas exchange otherwise no oxygen can get in to your water, a plastic cover will make the situation worse as this will decrease the amount of oxygen getting in to your water at surface level.

If you have a skimmer then your oxygen in the water should be ok

 

[candelloro]

Salinity and temp?

sg-1.025
Temp-77

 

[Hemmdog]

sg-1.025
Temp-77

Nice. Yea must be lack of oxygen then.

 

[Ly78]

You can try removing the lid for awhile and see if it makes a difference. Ive had diatoms for months with fishes in and they are doing fine. Mine is open top tank btw.

 

[N8 the Gr8]

Imo, 2.5 gallons is not fit for a fish. At least, in the sw hobby. Eventually diatoms die off as they split and reproduce asexually and the more they split, the weaker they get. Algae and diatoms feed off of not just nitrates but could be silicates of phosphates and do not deplete oxygen. Rather, they create it through photosynthesis and take CO2 from the water. Simply put, It is highly unlikely that it is an oxygen problem. It could possibly be a parasitic problem, like “gill flukes”. It is quite plausible since your corals are doing well. I would need to know other symptoms. It quite possibly could just be that the tank is too small. Stick to inverts!

 

[ScottR]

I’d say that a 2.5 isn’t enough for fish to get enough oxygen. Especially with other life in the tank. I wouldn’t blame diatoms for that.

 

[Craigdoc]

I agree, it's a very small body of water, no skimmer and a plastic cover, the oxygen will depleat very quickly.

I wouldn’t rule out disease or parasites though but instantly gasping at the surface is a sign of poor oxygen, a lot of parasites effect the fishes breathing though as they attack the gills.

 

[candelloro]

I agree, it's a very small body of water, no skimmer and a plastic cover, the oxygen will depleat very quickly.

I wouldn’t rule out disease or parasites though but instantly gasping at the surface is a sign of poor oxygen, a lot of parasites effect the fishes breathing though as they attack the gills.

They never gasped at the surface, basically what happened with my first clown goby was he swam normally and perched and ate but was breathing fast the whole time, even in the plastic bag. All my fish were breathing fast in their bags from the store but were breathing normally in the store tanks.

 

[Hemmdog]

They never gasped at the surface, basically what happened with my first clown goby was he swam normally and perched and ate but was breathing fast the whole time, even in the plastic bag. All my fish were breathing fast in their bags from the store but were breathing normally in the store tanks.

Check and see what they keep their salinity at, some places keep it ultra low to try to limit disease. Salinity shock could be a possible culprit.

 

[Craigdoc]

The breathing fast is probably stress I would assume, like us the faster you breath the more oxygen you use.

To me it sounds like oxygen depilation to die so quickly but I certainly wouldn't rule out disease, if your previous fish have used up the majority of oxygen in your system then the plastic cover on top is not allowing the levels to build back up before you put your nest fish in, that's just a theory, I wouldn't rule out disease though

 

[ScottR]

They never gasped at the surface, basically what happened with my first clown goby was he swam normally and perched and ate but was breathing fast the whole time, even in the plastic bag. All my fish were breathing fast in their bags from the store but were breathing normally in the store tanks.

A lot of stores use air instead of oxygen to fill their bags. So they need to be put in a well-aerated tank to come back to normal. I have a 40g tank and I have a powerful pump that splashes the water on the surface to ensure there’s enough oxygen in my tank. Also, that is a rather large bio-load. I recall you saying you’re setting up a 20 gallon. Perhaps wait until that tank is ready to go before adding any more animals.

 

[candelloro]

Check and see what they keep their salinity at, some places keep it ultra low to try to limit disease. Salinity shock could be a possible culprit.

I think that might be it. I normally only drip acclimate around 45 minutes to an hour. Should I acclimate longer? My store keeps their salinity around 1.019-1.020

 

[candelloro]

A lot of stores use air instead of oxygen to fill their bags. So they need to be put in a well-aerated tank to come back to normal. I have a 40g tank and I have a powerful pump that splashes the water on the surface to ensure there’s enough oxygen in my tank. Also, that is a rather large bio-load. I recall you saying you’re setting up a 20 gallon. Perhaps wait until that tank is ready to go before adding any more animals.

A clown goby has a large bioload?

 

[N8 the Gr8]

I wouldn’t rule out disease.

 

[Craigdoc]

Co

A clown goby has a large bioload?

Compared to other fish no but in 2.5g yes I would say it is.

I think if you drip acclimatised for that long then you'll be fine in my experience

 

[ScottR]

They never gasped at the surface, basically what happened with my first clown goby was he swam normally and perched and ate but was breathing fast the whole time, even in the plastic bag. All my fish were breathing fast in their bags from the store but were breathing normally in the store tanks.

Dbl post

 

[N8 the Gr8]

Co

Compared to other fish no but in 2.5g yes I would say it is.

I think if you drip acclimatised for that long then you'll be fine in my experience

Water quality isn’t the issue though. Because the corals are thriving, there is reason to believe that it could be disease related or the fact that Having too small of a tank could stress out the fish.

 

[Craigdoc]

Water quality isn’t the issue though. Because the corals are thriving, there is reason to believe that it could be disease related or the fact that Having too small of a tank could stress out the fish.

I would imagine that fish need more oxygen than a couple of small corals and crabs but I couldn't say that I'm 100% sure on that