Coral dying need help

[Brandonyoung129]

Need your help, have a year old tank and my corals are slowly dying or just existing. 6 months ago I had good coral growth then monti’s started dying and the rest of corals growth mostly stopped to the point of just existing. I have tested water with typical parameters below. i have focused on the removing phosphate and raising nitrate for the last 3-4 months and the tank just seems to be getting worse. Looking for suggestions as Im thinking of setting up dosing nitrate, Carbon, alkalinity and calcium to see if that can get my water squared up. Parameters below. I have no algae (Zero) in tank and all 10 fish are doing great.
phosphate .30 (has been as high as 1.6)
nitrate 5ppm
dkh 7.0
Ca 415
salinity 1.026
temp 76
100 gallon tank with sump and curve 7 skimmer, no refugium
lights are Hydra 32’s

i Have used every phosphate remover known and the best number I have gotten is .25.

 

[Dkmoo]

A few thoughts:
1) phos is def too high. Are you feeding to much? Consider lowering whatever nutrient you put into the tank by 50% and see if it makes a difference. What are you feeding? Check the ingredients to see maybe one has high phos

2) whats PH? Low ph can inhibit coral growth. Looks like your alk is a bit low. I would also suggest dosing sodium carbonate (soda ash) instead of sodium bicarbonate (like the red sea B) if your PH is on the low side.

3) Cal could be a little higher but shouldn't be a major contributor to your issues at corrent levels

4) whats ur mag? Having 1300ppm should help keep alk/ca balance.

My suspicion of whats happening in your tank is that bc you had no algae, there is no biological process to absorb the Pho so over the year all that Phos from the fish poop has been saturated in the rocks and sand that's acted like Phos batteries that releasing it back into the water. You also said you have 0 algae which might actually be making ur situation worse bc algae usually absorbs phos which can the be removed from ur system when you physically pull the algae out. A possible low ph inhibiting coral growth + no algae means there's no absolutely no biological process to pull phos out of the water.

I would try to set up an algae scrubber or turn the sump into a fuge. Also do a deep cleaning/vacuum of the sand to remove all the gunk buried in the sand that's acting like the phos batteries as a start and reduce feeding for a few months.

This is a problems that accumulated from the whole year of imbalance in your tank so will take a few months minimum to correct. Be patient.

 

[Brandonyoung129]

Thank you Dkmoo for your thought. I think you are on to something with the phos battery. My LFS also commented about my used rock structure being a source of phosphate leaching. Replacing rock structure seems a little aggressive at this point.
The plan is to get my dosing and refugium set up as long term I will need both and incorporate a standard testing regime.

 

[JGT]

Also, can’t see from pic but how is your flow? It’s very important to bring nutrients and take away waste from the corals which will help with growth.

 

[Uncle99]

Are you getting that phosphate number from a Hanna ULR phosphorus checker?

I was stuck on .25ppm for 6 months, tried everything, only to find out is was the test kits, API, Seachem and Salifert.

If you are .3ppm, certainly that will slow coral growth as your nitrates look fine.

With 5ppm nitrate, I would be running 0.03-.1ppm phosphate.

A good GFO will mop up that organic but make sure you test frequently and “pull” the GFO when in the above range.

 

[Tmtdvm]

Good ideas. I had a 40g that was high in PO4 as well and could not get it to go down until I stated vacuuming the sand completely. My flow was also an issue so I added 2 MP10’s to my system. I quit feeding high nutrient pellets and flakes and went to frozen cubes and limited feeding to once a day. It really helped me out. Additives only put a bandaid over the problem but do not correct the issue.