can live rock retain phosphates

[julioperez01]

As the title states i am curious as to the answer to this question... it seems that i have an extremly high phosphate reading with my Hanna digital tester. It is new and in the past week i have done 3 tests all 3 tests have come back reading 0.36, 0.39, and last night 0.34

My tank is all sps and all seem to be doing fine... My tank is a 150 gal with a sump and i change about 5 gallons weekly i clean the glass about once every 4 days or so.

[Psyops]

Do you have a lot of sand? That can retain phosphates also over time. My old tank crashed because of that. I did not have a CUC due to having a lunar wrasse. As to your rock question, I have been told yes also, but more so with the sand. That is if you have any sand. The way I control it better now is doing 10% weekly water changes. More like 15 gallons a week for you. I don't know what else you got as filtration though. Do you long press the reading part when you are taking the final reading? Are you making sure that all of the powder is dissolved in the vial before the reading? Are you taking water samples from an area of the tank that has some solids in it? All these can have false high results with the Hanna tester. Whatever it's worth.

[julioperez01]

I have less than 1inch of sand on the bottom. I make sure the powder is all dissolved and i get the water from the front of the tank where there is plenty of motion and no dead spots.

[M007]

LR can leech P04 as much as sand. P04 can also come into you system through other things such as fish food or a poorly maintained RO/DI. If your coral look good and you have little to no nuisance algae I wouldn't do anything too extreme at this point. My Hanna readings have been .60 for the last 4 months and my coral look great with no nuisance algae of any kind. When I was reading 0.08 my coral colours were crappy and growth was pathetic. I believe a little P04 is a good thing. Please no verbal assaults. :hmm1:

[Psyops]

Good point M007. Sometimes the best thing to do is just watch your corals. If the rocks a leaching out PO4 then just doing constant weekly water changes should keep it at bay. Always a good habit with SPS dominant tanks. I have learned that the hard way.

[julioperez01]

May be a stupid question... but could the rocks eventually release all the phosphates they have and be phospate free?

[SaltwaterAdict]

Good point M007. Sometimes the best thing to do is just watch your corals. If the rocks a leaching out PO4 then just doing constant weekly water changes should keep it at bay. Always a good habit with SPS dominant tanks. I have learned that the hard way.

+1 to weekly waterchanges, helps keep things stable.

[drw94]

I believe LR can retain PO4. I used to use kalk mixed with top off water. From my understanding kalk binds to PO4 and gets retained in LR. My tank currently reads 0.00 PO4(hanna meter) but I have some bryopsis growing. I thinks this is because the algae is using the PO4 before it gets released into the water column. I have since switched the BRS two dosed via dosing pumps. Just my opinion and experience.