Guidance on stabilizing basic water quality

[Head Case]

adopted a 7yr 75gal FOWLR tank at the end of February. Took a bit to get settled, but we got the nitrates under control with fewer feedings and weekly water changes. Nitrates are hanging around 10pm, with fluctuations between 5-15. Got excited and bought some frags. They all did well except for a montipora Digitata which quickly deteriorated. Took a water sample to LFS, and phosphates were crazy high. 2ppm. Tried the green pads and some GFO in a filter sock inside our canister filter. Switched to frozen food only. No real progress, maybe down to 1-1.5, so I got a GFO reactor. Got it running Monday night. Checked phosphates this morning, and they appear to be 0.5. I’ve got 7 tblsp bulk BRS GFO (less than the 9 tblsp BRS recommends for 75gal) running as slowly as the ball valve will allow.

I’m excited that the phosphates are down, a little confused/concerned how quickly they came down (was expecting this to be a weeks long process), but mostly want to make sure I land this plane gently. Should I keep the reactor running? Monitor daily to make sure it doesn’t go to 0? Turn it off to let everything acclimate and monitor whether phosphate goes back up? Then restart it in another week or two?

I’m all ears! Thank you.

 

[exnisstech]

GFO strips PO4 very quickly so you have to be careful with it. I rarely use it but when I have I use about 1/4 of the recommended amount and change as needed. Often it only last one day.
I'm not as knowledgeable as many here but I would pull the gfo and just monitor and see where the tank lands and watch for a while. I would rather have P04 of 0.2-0.5 doing nothing than constantly working to keep it at 0.02 or similar. A lot also depends on how the corals react to determine what level is best for the tank. I run 3 tanks all at different levels with no intervention but the levels are stable on all which is important JMO.

 

[PharmrJohn]

Did you add any old dry rock to your tank?

 

[Head Case]

Did you add any old dry rock to your tank?

Rock that had been in place for 7yrs was all moved and set back up. The tank cycled and then settled back down. LFS said that phosphate could be leaching out of the rock after all those years and that a reactor might be needed to bring the levels down.

 

[PharmrJohn]

Ohhhhh! I thought it was an ACTIVE tank. It's definitely your rock. And it'll be this way for months. I am in the same situation with my rock. But I'm curing it first before restarting. It'll take 6 to 12 months from start to finish. You're in it for the long haul unfortunately.

 

[Formulator]

I had the same issue after rebooting an 8 year old tank that I had neglected. I’ve been battling phosphate for 3 months. Started at 2.5 ppm and have it stabilized around 1 ppm now. Still chipping away at it with GFO, but it takes time to get it all out of the rocks. You may be at 0.5 ppm now, but I suspect when the GFO is exhausted, the rock will re-equilibrate back up closer to 2 ppm over a couple days. The hope being that it stabilizes slightly lower (maybe 1.5-1.8 ppm) and you start another round of GFO. Then just keep repeating the process until you get to your target. I’m shooting for 0.1-0.2.

 

[Head Case]

Ohhhhh! I thought it was an ACTIVE tank. It's definitely your rock. And it'll be this way for months. I am in the same situation with my rock. But I'm curing it first before restarting. It'll take 6 to 12 months from start to finish. You're in it for the long haul unfortunately.

It is an active tank? The people had it going at their house, and we took their entire rig, fish and all. We set it back up within an hour of emptying it and moving it.

Still same issue, long haul plan? That’s ok if it is, my biggest worry is overdoing the GFO and crashing the tank a different way. I have no problem running the reactor if that’s what it takes to keep things in check!

 

[PharmrJohn]

Huh! Strange. Did the individual who sold you the tank give you ANY clue as to what kind of parameters he was running? If they overfed and had through the roof PO4, it could have leached into the rock anyway......

 

[PharmrJohn]

As I'm thinking about it, it HAD to be the last owner. PO4 issues ike this don't happen overnight. So that absolves you. Yes, I would say you are in for the long haul. Manage it the best you can until nature takes its course and the PO4 leaves the scene. But your gonna have to create a gradient whereby the P04 WANTS to leave the rocks. This is where my knowledge base breaks down a tad. If there is a Reactor you can set up to create a constant low level, I would go that way. Other than that, listen to others for ideas on the how to.

 

[Head Case]

Huh! Strange. Did the individual who sold you the tank give you ANY clue as to what kind of parameters he was running? If they overfed and had through the roof PO4, it could have leached into the rock anyway......

Their daughter ran it for a few years while she was in school for marine biology then moved off from home. They kept it running but didn’t maintain it (didn’t clean the filter for a year, power heads all honked up, etc). I’m sure the water was really rough. Heck we picked out all of the foil from frozen cube feedings over the years but we still find foil pieces that the snails uncover.

 

[Head Case]

As I'm thinking about it, it HAD to be the last owner. PO4 issues ike this don't happen overnight. So that absolves you. Yes, I would say you are in for the long haul. Manage it the best you can until nature takes its course and the PO4 leaves the scene. But you’re gonna have to create a gradient whereby the P04 WANTS to leave the rocks. This is where my knowledge base breaks down a tad. If there is a Reactor you can set up to create a constant low level, I would go that way. Other than that, listen to others for ideas on the how to.

Ok thanks. I’ve got the reactor running so I’ll just keep a close eye on the water parameters.

 

[danreef55]

Hi Head Case,
Sorry you are encountering this issue. A few things you might want to consider before deciding on root cause.

1. You probably have done this already but check the output of your RODI unit.
2. Take a piece of rock and place it into a container or fresh saltwater. Wait two days and test. If the phosphate rises you have your root cause.
3. Using a separate container take a small amount of sand from the display perform the same test & pray this is your issue! Then it is only a matter of removing the sand and either run bare bottom or use new live sand.

Regarding keeping the phosphate levels in check.
Do you have a way of incorporating a refugium with your system? It is great to have a fuge regardless imo

Best of luck
Dan