Will chaeto remove phosphate if there is no nitrate present?

[drdripp]

Tank was running at 0.35ppm phosphates and 0 nitrates, due to a refugium that I've had since it cycled. I just got my Hanna checker for phosphates recently so I had never measured it before. I did a 15 gal water change today to bring it down, but it's still at 0.28ppm.

I read that chaeto is supposed to be able to control both nitrates and phosphates. Is it starving from no nitrates, and is that why it's not removing the phosphates?

Another possibility is that I'm overfeeding, because I feed twice a day.

Unless it's something completely different that I'm not aware of...

Refugium:
5 gal refugium with chaeto, 6 hours of purple grow light each night (changed to just 3 hours yesterday), aragonite bed
5 lbs. of rock

DT details:
20 gal with 2 juvenile clowns and 2 fire shrimp, aragonite bed, 12 hours lighting with sunrise and sunset
Protein skimmer, Aquamaxx Bullet-1
10lbs. of rock
No unusual algal growth in DT

All other measured params seems OK:
Temp: 79.2 deg F
Salinity, SG: 1.024 (raised to 1.025 in water change)
Ammonia: 0.01ppm
Nitrite: 0
Nitrate: 0
dKH: 11.2
Ca2+: 400ppm
Normal behavior in tank inhabitants.
Occasionally dose calcium for coralline algae (don’t have it yet but want to stay in a good range).

 

[Miami Reef]

Cheato needs nitrogen and phosphorus to grow. If nitrogen is limiting, then it can’t grow/consume phosphate.

I would dose nitrate or ammonia in your case.

 

[RedoubtReef]

Is your cheato growing? if it is, then its doing the job and getting what is needed. If it's shrinking then it is not.

 

[Randy Holmes-Farley Verified Community Expert]

Yes, everyone so far is correct. It needs N to grow, but might or might not be getting enough without nitrate being detectable. Dosing N and maybe iron could be useful

But the idea that it will "control" nutrients only is a vague reference to the idea that it takes up N and P. You may just not have enough to do the job, or it is not lit enough, wrong flow, etc.

There are all sorts of reasons that phosphate may accumulate when using macroalgae.

 

[jda]

My chaeto grows like crazy with no3 of .1, or so. I likely have lots of nitrogen via other sources since I feed a lot... most likely ammonium.

Chaeto needs other trace elements, like iron. You should be good with iron if you did a larger water change, but if it had been a while then this can explain slow growth.

 

[Miami Reef]

My chaeto grows like crazy with no3 of .1, or so. I likely have lots of nitrogen via other sources since I feed a lot... most likely ammonium.

But how effective is it at removing phosphates? Probably will take a lot of ammonia/nitrate to remove over 0.2, especially with a the extra amount bound to the rocks and substrate.

If he feeds a lot, he will be adding nitrates and phosphates in almost equal ratios.

I think the most logical solution is to use lanthanum chloride or GFO to bring down the high PO4, and use the cheato to maintain the lower levels.

 

[Miami Reef]

Organisms use much more nitrogen in proportion to phosphorous. I’m not a fan of growing organisms for excessive phosphate levels, especially since there’s an extra large reservoir bound to calcium carbonate.

 

[drdripp]

Slow growth in chaeto hasn't been an issue. The chaeto has doubled in diameter (originally baseball size) since I got it 18 days ago. I've bought some sodium nitrate and will begin dosing it once I get it. I'm not super comfortable adding ammonia directly...

Thank you everyone for the helpful information!

 

[TastyScrants]

Yes, everyone so far is correct. It needs N to grow, but might or might not be getting enough without nitrate being detectable. Dosing N and maybe iron could be useful

But the idea that it will "control" nutrients only is a vague reference to the idea that it takes up N and P. You may just not have enough to do the job, or it is not lit enough, wrong flow, etc.

There are all sorts of reasons that phosphate may accumulate when using macroalgae.

Hi Randy,

What are some of the reasons for phos accumulation when using macroalgae?

I’m having phos slowly build up in my tank. For the last few weeks my chaeto has been growing like crazy and mopping up nitrate. Around 1 month ago I removed my roller filter and instead started a refuge mainly for greater biodiversity. I no longer run mechanical filtration unless doing weekly maintenance. I do use a skimmer rated to 300L in SPS tanks (my tank is a reefer 250)

I haven’t changed feeding habits, and I have been controlling my nitrate level by adjusting my chaeto photoperiod accordingly. My nitrates are between 4-7ppm as a result, this has also allowed me to cease carbon dosing which was giving me Cyanobacteria.

Unfortunately though my phos is slowly starting to accumulate. I have been dosing LaCl for several months directly into my skimmer, which was holding my phosphate at 0.06ppm

Today it is 0.19ppm but algae is managed by competition with chaeto and a robust cleanup crew. I have not changed feeding habits, my fish still get 2 cubes of TMC gamma frozen food (UK brand) once a day.

My alk consumption is increasing week on week so I do think my SPS are growing.

I’m due an ICP, however I’ve checked my phos level with 3 different test brands.

My last ICP had high iron (found rust on a saltwater marketed cleaning tool) which I attribute to my chaeto success. I do have some chaeto-gro on standby when it depletes.

 

[jda]

Biological control of po4 is often not effective. I used to have a 125g refuge attached to a 300g FOWLR and it could only maintain po4 levels, not lower them... and I removed multiple 5g buckets of algae every week, or so.

I use 3 or 4 skimmers in every tank and run a larger fuge and that seems to keep them stable.

It is very common to need media or chemicals to lower po4 and in some cases to just to maintain it.

 

[Randy Holmes-Farley Verified Community Expert]

Hi Randy,

What are some of the reasons for phos accumulation when using macroalgae?

Unbalanced additions, unbalanced exports, or just more nutrients than export can handle.

One simple concept is that since it is possible for N (nitrate) to be removed by denitrification (which does not remove phosphate), that N can become limiting for phosphate export if one is only using balanced export methods (such as growing macroalgae).

Also, different macroalgae take up somewhat different ratios of N : P, so if that ratio does not match the foods added, phosphate can rise.

 

[Dan_P]

Tank was running at 0.35ppm phosphates and 0 nitrates, due to a refugium that I've had since it cycled. I just got my Hanna checker for phosphates recently so I had never measured it before. I did a 15 gal water change today to bring it down, but it's still at 0.28ppm.

I read that chaeto is supposed to be able to control both nitrates and phosphates. Is it starving from no nitrates, and is that why it's not removing the phosphates?

Another possibility is that I'm overfeeding, because I feed twice a day.

Unless it's something completely different that I'm not aware of...

Refugium:
5 gal refugium with chaeto, 6 hours of purple grow light each night (changed to just 3 hours yesterday), aragonite bed
5 lbs. of rock

DT details:
20 gal with 2 juvenile clowns and 2 fire shrimp, aragonite bed, 12 hours lighting with sunrise and sunset
Protein skimmer, Aquamaxx Bullet-1
10lbs. of rock
No unusual algal growth in DT

All other measured params seems OK:
Temp: 79.2 deg F
Salinity, SG: 1.024 (raised to 1.025 in water change)
Ammonia: 0.01ppm
Nitrite: 0
Nitrate: 0
dKH: 11.2
Ca2+: 400ppm
Normal behavior in tank inhabitants.
Occasionally dose calcium for coralline algae (don’t have it yet but want to stay in a good range).

Chaeto is used to consume nitrates. In the process of consuming nitrates it is also growing and needs some phosphate, not much though. Phosphate is removed by GFO or lanthanum chloride. Be careful not to starve your fish in an attempt to control phosphate.