Leaching phosphate from rock

[wagadodo]

Hi all, my tank is 3 months old and I have made the decision to cycle some Caribsea life rock away from my main display which is eventually going to replace existing rock in my tank, as I believe my crazy high phosphate levels of 0.21ppm are being caused by leaching phosphate from the rock that I’ve used which was previously live, then allowed to dry out and then used again with out curing. Before I go ahead with this, I’m interested to know if anyone has done a similar process to this and what tips would you give?

 

[Rtaylor]

.21 isn’t crazy high.

 

[wagadodo]

.21 isn’t crazy high.

What would you suggest to get those levels down? I’m already running 50g of gfo in a media bag, I feed 3 times a week and I do 10% weekly water changes. I’m not running a skimmer so I cant carbon dose

 

[Rtaylor]

What would you suggest to get those levels down? I’m already running 50g of gfo in a media bag, I feed 3 times a week and I do 10% weekly water changes. I’m not running a skimmer so I cant carbon dose

You probably don’t actually need to decrease it. But lanthum chloride would do the trick.

 

[TheBear78]

As above, 0.21 might register as higher but certainly not crazy high.
I'm currently maintaining 0.3 and about 35 ppm nitrate and everything is happy so I'm gonna leave it there.
Most rock will absorb phosphate for a period (where water tests show a low or non existent level) while we're typically overfeeding to bring the numbers up. Once saturation point is reached it then leaches back into the water and we see "high" numbers. We then battlemto bring them down!
This will happen to all rock eventually but it's typical in a new tank. I sat at zero for weeks before carefully dosing but as soon as the levels started to rise it shot up and I am now using GFO to maintain it where the coral seems happy.
I found that GFO in a bag did nothing. It was in a high flow area but every time I checked it had just clumped. Since running a small reactor it has been much more efficient and also predictable. I use a heaped tablespoon every two weeks. No idea how much that weighs!