Carbon Dosing not lowering phosphate

[flying4fish]

I'm running a Red Sea 170 and it has been established for 5 years. For years phosphates were extremely low, so low that I stopped checking. But when some of my corals began to recede I began testing everything and found nitrates at 20ppm and phosphates. .22ppm. I began carbon dosing in May. By the end of May nitrates were at 0, but phosphates still high. I began dosing nitrates. Four months later phosphates are still high...even higher than when I began. I'm barely feeding my fish and corals (frozen mysids), yet phosphates are rising. I suspect the rise is due to all the corals that are dead and dying. I'm about to throw in the towel after 5 years and just quit the hobby. My sump is so small there really isn't room for a GFO reactor, and I've read some people believe they've lost corals to GFO. But to be honest I haven't done a huge amount of reading on the topic because it's not an easy option for me.

I tried a product that had lanthanum chloride, but it just seemed to accelerate my loss of corals with very little impact on my phosphates. I think some of the coral loss was due to large swings in alkalinty that occurred as a result of the carbon dosing. My alkalinity has been so stable for so long that I only test once or twice a month, so I was flabbergasted when I found levels had risen to 13.6. I didn't know that could happen when you carbon dose. I still don't really understand what makes that happen, but I certainly went through some up and down swings as I tried to determine the new level of alkalinity consumption (greatly reduced, from 42ml/day to 10ml/day).

I'm wondering if others have gone through this and if they found a solution?

 

[Randy Holmes-Farley]

I’d stop carbon dosing or dose nitrate. Carbon dosing is not very effective at phosphate reduction and will drive nitrate into the ground before doing much for phosphate for a three entirely different reasons:

1 organisms such as bacteria contain a lot more N than P.
2 denitrification lowers nitrate and not phosphate
3 phosphate bound to rich and sand makes it much harder than nitrate to be reduced

 

[flying4fish]

I’d stop carbon dosing or dose nitrate. Carbon dosing is not very effective at phosphate reduction and will drive nitrate into the ground before doing much for phosphate for a three entirely different reasons:

1 organisms such as bacteria contain a lot more N than P.
2 denitrification lowers nitrate and not phosphate
3 phosphate bound to rich and sand makes it much harder than nitrate to be reduced

It's easy to stop dosing carbon, but I still need a very effective method for reducing phosphate. So far it's a battle I've been fighting for a long time with zero progress. In the meantime I've lost a small fortune in corals.

 

[stovenut]

Why not buy bags of Chemi Pure Elite? They sell 6 packs on Chewy and Amazon for about $38. Should be room for a bag in your AIO. Change out the bags every 4 weeks. Use until your phosphates drop under .1. But honestly phosphates at .22 is not terrible. And as you know, if you have healthy corals they will also help lower your phosphates. Get your tank stable, mitigate coral losses, and you will be good to go.

 

[flying4fish]

Why not buy bags of Chemi Pure Elite? They sell 6 packs on Chewy and Amazon for about $38. Should be room for a bag in your AIO. Change out the bags every 4 weeks. Use until your phosphates drop under .1. But honestly phosphates at .22 is not terrible. And as you know, if you have healthy corals they will also help lower your phosphates. Get your tank stable, mitigate coral losses, and you will be good to go.

I'm not sure what you mean by "room for a bag in your AIO;" I thought that meant All-in-One aquarium? During this phosphate battle I did buy Phos FX resin and put them in a bag in my sump (placed it in my filter sock), but there did not seem to be enough water flow for it to work. My phosphates did not drop. My current phosphate level is .3ppm...that's pretty high? To be honest, all the corals were OK until I started trying to reduce phosphates. It seems everything I do has just made matters worse. Very frustrating.

A bit more info. Yes, I use and regularly clean filter socks. Yes I run a protein skimmer (which has been very active since I started carbon dosing).

 

[stovenut]

Yes. In your all-in-one... In your filtration chamber or sump or whatever space you have that has high flow. You can drop them into your filter socks or below your filter socks or at the baffle right before your return pump chamber. They will reduce phosphates. Or you can purchase some high capacity gfo and make your own bags. I don't know of a more proven method to remove phosphates safely than using gfo in a reactor or bags. And I've never read anything about it causing problems. I hope you find success. I'd go the gfo route and stick with it.

 

[Randy Holmes-Farley]

I don’t think there’s a big urgency to lower it.

 

[hexcolor reef]

If coral are dying off, maybe it’s due to ALK fluctuations. If you allowed the nitrates to reach around 40ppm with phosphate at 13ppm currently your tank would be more balanced out.

How’s the PH in the system? How’s the water quality any cloudiness

 

[bushdoc]

Carbon dosing and increased DOC ( dissolved organic carbon) may change composition of "coral holobiont" and increase growth of undesirable bacteria as well as desirable ones. There are field studies indicating that increased DOC may be more harmful to corals than elevated levels of phosphates or nitrates.
I am aware that this is not particularly popular theory on R2R forums, but I am firm beliver that carbon dosing is advanced technique and can be detrimental to reef tank inhabitants even when applied by experienced reefers.

 

[Nano_Man]

For phosphate removal that doesn’t kid on removal it’s L chloride but do your sun if using you can bottom out no problem. But remember that after you lower it it will in a day or so go back up due to it
Leaching out of your Rock and sand until that comes out it will be up and down for a bit . You would need to speak with @Randy Holmes-Farley I am no expert but he is