Why are my phosphates up

aaron186 · Jun 17, 2024

I have an 18 month 100 gal tank that is using Marco rock and Carib sea sand. I have a filter roller, chaeto fuge using a Neptune gro, and a octo elite 150 skimmer, plus a UV sterilizer. I’m feeding avast marine reef jerky (about 2 cubes equivalent per day).

My tank previous suffered from 0/0 phos and nitrates. About 3 month ago I had a Dino outbreak and eventually beat it last month by dosing N and P (brightwell) and a quarter dose of waste away followed by microbacter 7. My phos at the time of thinking I was all clear was 0.1 and nitrates 10. Checked on Hanna checker and confirmed previously with Nyos kits.

Since beating Dino’s my phos has climbed to 0.26. Nitrates have stayed solid at 10. I stopped dosing Phos and nitrate a month ago (dosing half of what Brightwell recommended on bottle). I do 1.4% daily autowater changes (40% monthly). I did a one time large water change of 20% in addition to the daily changes with vaccuming my sandbed (so roughly 60% this month). I cut back my food a little. I’m skimming wetter. Still my phos isn’t budging below 0.21. Nitrates hovering around 6-5. Nothing seems to have died. I started dosing with Tropic Marin Elimi NP carbon dosing this week. No changes. Any thoughts on why my tank would suddenly go from 0/0 nutrients for over a year and then shoot up after I got rid of Dino outbreak? Any suggestions? Should I just be patient with carbon dosing?

KrisReef · Jun 17, 2024

Once the rock substrates get saturated with phosphate they tend to stay in equilibrium. Removing P from the water column causes the rock bound P to go into solution and the number can tend to stay stable while you remove it. At some point, the rocks will be fairly P free and the number you measure in solution will start tumbling down, maybe hit zero again after just the smallest does P remover.

Gl, go slow and you will get there someday.

Lavey29 · Jun 17, 2024

There is nothing wrong with .26 phosphate if your tank is doing well overall.

aaron186 · Jun 17, 2024

Lavey29 said:
There is nothing wrong with .26 phosphate if your tank is doing well overall.

Hopefully Randy will correct me if I’m wrong eventually, but I thought I read a couple of articles by him that higher phosphate can limit coral calcification. Tank is algae free currently but my acros aren’t growing very fast. The other SPS seems to be doing well. Hoping to optimize things as best as possible and to understand what’s happening in the tank.

Lavey29 · Jun 17, 2024

aaron186 said:
Hopefully Randy will correct me if I’m wrong eventually, but I thought I read a couple of articles by him that higher phosphate can limit coral calcification. Tank is algae free currently but my acros aren’t growing very fast. The other SPS seems to be doing well. Hoping to optimize things as best as possible and to understand what’s happening in the tank.

Not uncommon for acros to grow slow or base out first. Really high phosphate can do what you mention. My phosphate sits .2 to .4 and my SPS dominant mixed reef thrives. If you want to walk yours down a little just add a bag of phosguard to your sump flow.

eliaslikesfish · Jun 17, 2024

Lavey29 said:
Not uncommon for acros to grow slow or base out first. Really high phosphate can do what you mention. My phosphate sits .2 to .4 and my SPS dominant mixed reef thrives. If you want to walk yours down a little just add a bag of phosguard to your sump flow.

agreed, mine runs at .25-.35with a very healthy and fast growing LPS dominant tank