Phosphates increasing 10 month old mixed reef

[Aquariumaddictuk]

I've noticed A relatively sudden but steady increase in phosphate after months of steady readings.
Tank is 10 month old reefer 170 & was setup with AF dry rock.
I'm running GFO in a reactor alongside carbon
Both changed bi weekly.
Dosing vinegar in 1ml increments hourly during initial photoperiod.
RODI tests negative for phosphate.
Parameters as follows:
Alk 7.5
pH 8.2
Cal 430
Nitrate 2.9
Mag 1350
Phos .48

I'm feeding hikari marine pellets lightly daily & spot feed 3 salifert scoops of reefroids once per week.
Only changes are I've been dosing acropower at 2ml per day for the last 2 weeks.

In past I've noticed roids do raise phosphate heavily so I've used 1 salifert scoop nightly as broadcast to keep phos in .003 range & that worked well.ive since stopped this.

I'm puzzled.could acropower be raising phos(unlikely I think) or is dry rock leaching suddenly.acro & Monti are becoming paler & I've had some STN on some frags.
GFO brings it down slowly but the seasaw levels are worrying.

 

[jda]

Any supplenent can raise phosphates if it has phosphorous in it. Do we know what is in acropower, for real? They say amino acids, but they tell you what they are or the other ingredients.

Reefriods are reported by many to raise po4 quite a bit.

Aragonite binds phosphate to an equilibrium with the water. Over time, the rock fills up and the water column level starts to rise. You can add no more food or stuff than you ever have, but the rock is less able now to cover up an excess of phosphate.

 

[bobnicaragua]

I would stop feeding the corals for now, do a water change, and start changing your GFO weekly. That should get your phosphate levels dropping.

Once they get down, you can experiment with your maintenance routine to keep your phosphates consistent.

 

[MrGisonni]

Probably the food but I bet there is some formula to estimate how much phosphate is leached over time from your rocks. @Randy will know

 

[jda]

There is no formula since surface area cannot be determined. Also the phosphate cannot leach out - the phosphate is bound and cannot unbind unless the water column level is lowered. The rock is not contributing to the po4 level in the water - the rock actually keeps the water column level lower.

 

[Aquariumaddictuk]

There is no formula since surface area cannot be determined. Also the phosphate cannot leach out - the phosphate is bound and cannot unbind unless the water column level is lowered. The rock is not contributing to the po4 level in the water - the rock actually keeps the water column level lower.

Any data on phos leaking from carbon or GFO once exhausted?
I've no idea if this is possible or not tbh

 

[jda]

Almost any media that binds po4 also can unbind - aragonite, GFO, Aluminum Oxide. This is not an soak-up and leach thing - the binding has rules that need to be followed. GFO that is bound with po4 can also unbind if the water column level is lowered.

po4 does not bind to GAC. GAC does bind organics that can have phosphorous sources in them that could break down. This is different than a what happens with GFO, aragonite, etc.

IMO, it is best to quickly use small amounts of both GFO and GAC in a reactor and then get them out of there.

 

[Pod_01]

Just a suggestion, before you do more GFO etc… maybe try to confirm the PO4 value you are getting is correct. Try different test kit etc….

Based on the description it sounds like a lot filter types are used on relatively small tank GFO, GAC, Vinegar, perhaps skimmer etc…
Sometimes less is better, the idea is that coral act as a main filter and the other filter types complement the corals.

From my experience Montipora going pail is a sign that something is not right. For example quick drops in PO4…