How to manage sustainable, low phosphates but not zero.

[Fisherman Joe]

So my PO4 is now 0.12.

I’m unsure whether to dose Carbon and have the bacteria bring the PO4 down or to add a little GFO.

Any advice?

 

[Sallstrom]

Try a day or two with half the amount of food you usually feed. Keep meassuring the PO4 and that will give you an idea of how much PO4 you add with your food.
I run one coral tank now controlling PO4 with coral food. One coral food recipe for PO4 over 0,05 ppm, and one for under 0,05 ppm.

 

[Fisherman Joe]

Try a day or two with half the amount of food you usually feed. Keep meassuring the PO4 and that will give you an idea of how much PO4 you add with your food.
I run one coral tank now controlling PO4 with coral food. One coral food recipe for PO4 over 0,05 ppm, and one for under 0,05 ppm.

Yeah I have considered that but I have an automatic feeder that feeds small amounts 4 times a day.

I lost a few of my smaller anthias a few weeks back and I was worried I was under feeding. What I am feeding now is really what I would consider the minimum.

I think my refugium needs to catch up and I can manage it with dosing carbon for now, but how effective is a refugium in eliminating PO4 versus NO4.

I did end up with zero NO4 recently.

 

[Sallstrom]

Yeah I have considered that but I have an automatic feeder that feeds small amounts 4 times a day.

I lost a few of my smaller anthias a few weeks back and I was worried I was under feeding. What I am feeding now is really what I would consider the minimum.

I think my refugium needs to catch up and I can manage it with dosing carbon for now, but how effective is a refugium in eliminating PO4 versus NO4.

I did end up with zero NO4 recently.

Okay. These things I find fun to experiment with
The tank I mentioned earlier is an experiment tank which is controlled a lot, so I have taken the opportunity to play around. The idea is to feed a lot, but still run low nutrients.

The refugium you might boost with elements like Fe, I and Mn IME. You might also boost the growth by harvesting some every day. At least that's my experince.

For keeping PO4 steady we need to add NO3. We use different sources of N, mostly KNO3 and NaNO3, but also NH4Cl. My guess is that some aminoacids also might end up like NO3.

So in our case this is our export and import every day:

Export control
Harvest 0,5L macro algae
Dosing 1ml Ethanol 40%
Clean the skimmer every day


Import:
7 ml KNO3 (solution - 80g/1000ml RO)
5 ml NH4Cl (solution - 38g/1000ml RO)
10 ml Aminoacids - Red Sea B
Dose Fe, I, Mn for algae
Fish food (frozen)
Coral food (frozen)

All these are almost the same every day. Therefor a small change in the coral food is noticeable in a day or two, and I can say almost for sure that it is the change in feeding thats making the change in PO4.
So IMO, to find your way of keeping the nutrients at the levels you want it's good to just change one thing at the time. Otherwise it's harder to tell what did what.

And as I think you already know, when running algae refugium or dosing a carbon source for reducing or keeping control of PO4, you almost always end up having to add NO3(or at least N in some form). Otherwise the N will be depleted and the consumption of P will stop.


This last two weeks we've kept PO4 at 0,03-0,08 and NO3 at 0,2-1 ppm.

 

[Fisherman Joe]

Great advice. Thank you.

I dose acro power by two little fishies. It has amino acids. I dose 3ml a day just before the lights go off.

My NO3 was zero running a refugium and dosing 10ml of NOPO X daily. I’m not dosing intermittently dependant on PO4 but it’s creeping up.

I may consider dosing some fertiliser for the Refugium bit won’t that effect the algae in the tank? Or do you dose it at night so only the refugium (which is lit up) can benefit?

 

[Sallstrom]

Great advice. Thank you.

I dose acro power by two little fishies. It has amino acids. I dose 3ml a day just before the lights go off.

My NO3 was zero running a refugium and dosing 10ml of NOPO X daily. I’m not dosing intermittently dependant on PO4 but it’s creeping up.

I may consider dosing some fertiliser for the Refugium bit won’t that effect the algae in the tank? Or do you dose it at night so only the refugium (which is lit up) can benefit?

The coral holobiont and the macro algae need the same nutrients/fertilizer as the algae you don't want. So to try to starve out unwanted algae and hope that will solve the problem very often result in cyanobacteria and/or dinoflagellates, which are good at competing in very low nutrient water. And unhappy corals and macro algae.

I know "the reef school book" says "keep nutrients low to control algae", but I think grazers, stability and time are better ways to deal with unwanted algae. So keep adding nutrients if they are too low, and make sure you have a good team of grazers. I like urchins. The more the better. And Ctenochaetus tangs as extra help

We dose 24/7. I like to spread out the dosings so the changes in the tank will be as small as possible.

 

[mitch91175]

Sometimes be sure that when using an automatic feeder that the pellets remain in the tank and not go to the overflow. I know on one of my systems if I do not turn off the return my pellets go into the overflow. Then they decay in there.

 

[Fisherman Joe]

Sometimes be sure that when using an automatic feeder that the pellets remain in the tank and not go to the overflow. I know on one of my systems if I do not turn off the return my pellets go into the overflow. Then they decay in there.

I have little device that sits on the surface of the water so the food can only go straight down.

I had a few days with PO4 at 0.10 then it went to 0.12, I added a little vibrant to compete with the hair algae that’s growing (a tiny amount) at the back of my rock and the PO4 crashed to 0.0.

I am now running no GFO. Just GAC and skimming with my refugium. I have tuned my AI fuge light to 55% on all channels/colours and that’s running for 13 hours with a 1 hour ramp time.

My PO4 is holding at 0.02 now so I’m trying to feed less and see what happens.

 

[Fisherman Joe]

Ok. So I’ve left the tank running with minimal feedings for about a week, they get flake 4 times a day in little servings. Not running any PO4 or dosing carbon

I’ve found the PO4 hovers around 0.03 but then today I noticed lots of Cyano on the sand and after testing the PO4 is 0.00 again.

I really can seem to get consistent low PO4.

 

[Fisherman Joe]

Another update.

So after 3-4 days of holding a steady 0.02-0.03 PO4, it went to 0.0.

I decided to feed a cube of brine shrimp and it went back to 0.03.

This is just using my Refugium to combat PO4.

The next day I was concerned it would plunge back to zero so I fed some frozen Copepods. My PO4 are up to 0.08 now. Ok it’s own I’m not worried about this. The corals are starting to colour up well and even my strawberry shortcake (that went brown after my last PO4 shock rise about a month back) is starting to colour up again.

my only issue is the brown sand: any advice?

 

[Fisherman Joe]

Ok so I’ve decided to go back to GFO and feed heavy.

I’m worried about my fish going hungry. I would rather feed them well and not have to worry.

Lets see what happens to the cyano.

 

[Fisherman Joe]

Anyone have any input here?

Trying to facilitate a discussion but can’t do it alone.

 

[Randy Holmes-Farley]

So my PO4 is now 0.12.

I’m unsure whether to dose Carbon and have the bacteria bring the PO4 down or to add a little GFO.

Any advice?

Carbon dosing is not usually very successful in lowering phosphate.

 

[LRT]

Alot of great info in this thread. I am also having a hard time keeping phosphates in detectable levels.
Like a different poster in this thread I was reading the dyno thread and had ran my Nitrates to 0. At the time I did not know my test kit was faulty. I overdosed my Nitrates and bottomed out my phosphates.
Kinda wish I never did anything. Nothing was broken so I shouldn't have fixed it. Just a little nuisance algae but corals where thriving.
Wish I knew what my parameters N truly was before the overdose because I'd put it right back to where it was and forget it.

 

[Fisherman Joe]

I’ve gone right back to using GFO and feeding heavy.

 

[Graffiti Spot]

People who know how to use gfo correctly normally have pretty nice tanks I have found. I love using gfo but hate having to change it! Hahah.

 

[Fisherman Joe]

What are people’s thoughts on ChemiClean?

I can’t seem to kick this Cyano when my PO4 is jumping around.

 

[Fisherman Joe]

Ok so after going back to feeding a little more heavily and using GFO, my PO4 is holding around 0.06.

I’m adding more GFO to the reactor but the Cyano is getting worse. Not sure if I should supplement the GFO with some vibrant to try and out compete the Cyano. I don’t want to do too much to soon.

 

[Fisherman Joe]

I think I’ve made a breakthrough. I think the reason I was getting varying results with GFO alone is down to the flow rate on my reactor.

I have a Nyos reactor which isn’t the most practical design but it does allow me to put carbon in the top and GFO in the bottom and save space. I can open the top and replace the carbon easy.

Some time ago I was just using this reactor for GFO so I manually adjusted the inlet on the pump in the base station. When I twist the chamber to allow more or less flow it’s rather pointless as the base station was only outputting a low flow. So it was really low flow or low flow. Not churning over the GFO.

I now have the GFO tumbling slightly and I’m confident it will have a greater effect at reducing my PO4.

I picked up a Copperband Butterflyfish at the weekend so I’m feeding more frozen food and my PO4 has crept up to 0.11 despite running lots of GFO.

One thing that is concerning me slightly is my Cheato isn’t growing very well. A while back it was thick and lush. I’ve increased the spectrum output on the AI fuge light by 5% and added and extra hour to the “on time” If the light but it seems to have really retarded it’s growth. I’ve left the extra hour on the timer but put the spectrum back to 50% intensity.

Hopefully my Cheato will take over and I’ll need to run less GFO.

Since trying to run no GFO and have strict feeding, I’ve noticed a decrease in the pods in my refugium. Makes sense. Less extra food, less scavengers. I’m happy I’ve been through this experiment over the last few weeks but I’m going back to running GFO and feeding heavy.

Aiming to keep my NO3 around 5ppm (any lower and it seems to go to zero too easily).

I am also aiming to keep my PO4 at 0.02 but that’s proving tricky.

 

[Sallstrom]

I think I’ve made a breakthrough. I think the reason I was getting varying results with GFO alone is down to the flow rate on my reactor.

I have a Nyos reactor which isn’t the most practical design but it does allow me to put carbon in the top and GFO in the bottom and save space. I can open the top and replace the carbon easy.

Some time ago I was just using this reactor for GFO so I manually adjusted the inlet on the pump in the base station. When I twist the chamber to allow more or less flow it’s rather pointless as the base station was only outputting a low flow. So it was really low flow or low flow. Not churning over the GFO.

I now have the GFO tumbling slightly and I’m confident it will have a greater effect at reducing my PO4.

I picked up a Copperband Butterflyfish at the weekend so I’m feeding more frozen food and my PO4 has crept up to 0.11 despite running lots of GFO.

One thing that is concerning me slightly is my Cheato isn’t growing very well. A while back it was thick and lush. I’ve increased the spectrum output on the AI fuge light by 5% and added and extra hour to the “on time” If the light but it seems to have really retarded it’s growth. I’ve left the extra hour on the timer but put the spectrum back to 50% intensity.

Hopefully my Cheato will take over and I’ll need to run less GFO.

Since trying to run no GFO and have strict feeding, I’ve noticed a decrease in the pods in my refugium. Makes sense. Less extra food, less scavengers. I’m happy I’ve been through this experiment over the last few weeks but I’m going back to running GFO and feeding heavy.

Aiming to keep my NO3 around 5ppm (any lower and it seems to go to zero too easily).

I am also aiming to keep my PO4 at 0.02 but that’s proving tricky.

I saw Randy wrote carbon dosing to lower phosphate usually didnt work, so I might give my observations that shows it can be done if done carefully.

We've tested in a couple of reef tanks to dose ethanol 40% while dosing KNO3 at the same time(to not lower the nitrate). When we did this, the phosphate slowly decreased over time. But now we are talking months and some of the tanks were very large compared to hobby tanks. Anyway, we measured often and adjusted the dosage of ethanol and nitrate so we kept the nitrate level steady while the phosphate slowly decreased. I would only recommend to do this if you are careful with the dosages and ready to meassure often, to make sure you do it right.

When it comes to your tank, I think the phosphate level will "bounce" around a bit due to feedings and time of meassurments. One way I see that you might get to a reasonable stable value is if you avoid changing more then one thing at the time and then adjust only GFO OR food amount, depending on if the PO4 is rising or lowering.

If the algae stops growing, you could try to add iron and manganese and see if they start growing again. They might deplete some elements if you run a large refugium in my experience.