8 year old tank with 2.0 PO4 and zero Nitrate

[Formulator]

As the title suggests, my phosphates seem to be out of control at 2.0 and I somehow have zero Nitrates. The tank was neglected for a couple years after my daughter was born and essentially went for 2 years with no water changes or detritus removal and very few times emptying the skimmate (it just kind of constantly trickled over the edge). The CUC died off, but I recently replenished it. Lost a few fish during that time and never found them so I assume they just decayed/were consumed by the tank. I’m not proud of any of this, but it is what it is. Honestly its a wonder that the Nitrate isn’t through the roof too.

Anyways, I’ve just “renovated” the tank and it is looking great again, but for the life of me, I can’t seem to get the phosphate levels to come down. I am still battling a bit of hair algae, but starting to get it under control with manual removal and many snails helping.

I’ve done multiple 20% water changes, siphoned out tons of detritus from the sand bed, and I’ve most recently run Phosguard in a reactor for 5 days and saw no change in PO4 from any of these things. I just changed the phosguard media out so will see if I can make a dent with that in a few more days. I will be starting up a large refugium this week with chaeto.

The tank is a 120g mixed reef with (somehow) happy SPS, LPS, a couple leathers and a RBTA. Decent fish load with a blue tang, foxface, blue chromis, lyretail anthia, 2 clowns, cleaner wrasse, diamond goby, and a fairy wrasse. Also about 30 snails (turbo and trochus), a couple fighting conch, 10-15 hermits, and 2 cleaner shrimp. About 60% of the fish and inverts are new additions since the renovation over the last 6-8 weeks.

I run a 55 gallon sump with no mechanical filtration except filter socks I run on occasion if I notice water clarity issues, an octopus skimmer, carbon reactor, and recently a phosguard reactor. I have a RODI system with ATO. Also possibly noteworthy that I used to run ultra low nutrients with carbon dosing before the period of neglect.

Any suggestions for reducing PO4 this high and any clue how my Nitrate could be consistently zero still? Are they related?

Salinity: 1.026 (refractometer)
pH: 7.8-8.3 between day/night (Apex probe)
Temp: 78.2-78.8
Alk: 8.9 dKH (Salifert Kit)
Ca: 490 ppm (Salifert Kit)
Mg: 1290 ppm (Salifert Kit)
Nitrate: 0 ppm (Salifert Kit)
Phosphate: 2-3 ppm (Salifert Kit, between 1 and 3 on the color chart, closer to 3)

I know the Ca and Mg are a bit high, but thats what you get with Reef Crystals.

Thanks in advance for any suggestions you may have!

 

[kfisc]

Honestly, I'd say that's an expected phosphate level given the bio-load and everything doing well. I'd predict it lowering, but not in a huge way, once more time has passed and with the addition of the refugium and chaeto. It would be great to see pictures.

 

[Formulator]

Honestly, I'd say that's an expected phosphate level given the bio-load and everything doing well. I'd predict it lowering, but not in a huge way, once more time has passed and with the addition of the refugium and chaeto. It would be great to see pictures.

Really? Then what’s all the fuss I hear from people with 0.1 ppm phosphate saying THAT is a high level? I’m almost 100x the PO4 concentration that I hear folks running around here. If I do come to accept 2 ppm phosphate, should I consider dosing some Nitrate to at least get the ratio in check? Or is this one of those “its not broke don’t fix it” situations that I should judge based on the health of my inhabitants?

 

[kfisc]

Or is this one of those “its not broke don’t fix it” situations that I should judge based on the health of my inhabitants?

That's my vote. You have an old tank, renovated as it is; it's not a small tank, and you I assume have not only healthy inhabitants but growing as well? Anything much beyond 2 (and getting worse as time goes), I'd worry about, but if it remains stable, that's the range for your tank.

 

[Reefing102]

Seems high to me. As for lowering it, my guess is the rock may be holding a lot phosphates and releasing them. But if everything is happy, I wouldn’t be overly concerned until you start to add new stuff.

That said, the 0 nitrates is likely due to the hair algae and corals consuming them at a rate faster than they produce.

 

[wvned]

Lanthanum chloride
This is what I use. I have it on a doser.

 

[Scotty333!!!]

If you want to lower your phosphate then I’d recommend jbl phos ex ultra , when I hit 0.15 I run it overnight and it drops to 0.05 so I switch it off for a week and repeat, I will put it on a timer when I pass the diy store but for now it works
I’ve used all the others rowa etc but that one for me is the best

 

[Scotty333!!!]

Oh
As said , it’ll get down low and you’ll stop it and then likely get a rise a few times until the po4s leached out the rocks