Removing nitrates from offline reef

[Aquamechanic]

Bit of a crazy first post to the forum but I have a puzzle to solve and thought maybe some could lend some insight.

I'll try to keep the lead up to my question short (which may just lead to readers needing more info but ...).

I am a full time aquarium service provider and have client aquariums ranging from small goldfish tanks to large reef tanks. One of my main clients has a 450 reef. He started a large scale renovation and isolated the tank to attempt to keep it going rather then tear it all down. Everything was accounted for except one variable. The construction crew left a large electrical heater running one Friday last February and the main breaker for the house ended up tripping. Since no one was living in the house at this time the situation wasn't realized until Monday morning. Tank temp was 55 degrees and the reef was wiped out.
Given the amount of trade work going on I decided to just keep water flow and heat going in the main tank and allow nature to clean up the mess. It would be a year until the reno was completed anyway.
Now 10 months later the tank is crystal clear. I measured chem levels and the NH4 and NO2 are zero. The NO3 and PO4 however are off the scale (100+ ppm and 10+ ppm respectively). There is about 350 lbs of live rock.

Without starting over (draining tank and removing all rock) how can I reduce the nitrates? I know I will need to move the rock around and vacuum under it to remove the organic sludge but was hoping to deal with the nitrates/ phosphates organically before any livestock is ever introduced.

Would this task be possible with vodka dosing and heavy skimming? There are no animals in the system so risks associated with this technique are insignificant.

Thoughts and comments would be appreciated.

PS the reincarnated system will have a UPS backup to cover potential future power problems. Fool me once ...

 

[liven learn]

Well being a tank provider you know water changes and nitrates go hand and hand. Any kind of carbon dosing like vodka I wouldn't suggest. That increases all bacteria not just the good. Say you could have algea problems fast. Clean the sand and rock and do large water changes.

 

[Aquamechanic]

I should add that the tank will not be ready to start up again until spring/ summer next year and that other than powerheads and heaters there is nothing running in the aquarium. It is encased inside a plywood box with vapor barrier and has no light source.

Maybe starting fresh is better but I figured even after a catastrophic crash there was value in the aged water/ rock.

Does this make sense?

 

[IanWR]

I don't see any benefit to aged water. As for your aged rock, it's been stewing in 10+ppm phosphates for most of a year. The rock is certainly salvageable, but I would treat it like new pukani, i.e. "cook" it until the PO4 is down to acceptable levels. It may take time and effort (some combination of big w/c, LaCl, wet skimming, GFO, etc) but it can be remediated.

As for the nitrates, you may find that the big water changes you will do to lower the phosphates manage your nitrates along the way. If not, you could consider adding a RDSB (lots of good threads here on RC) which should take care of it going forward.

 

[Reefer07]

Water change is all you can do. Is there any livestock in the tank now or not really? If not I would do as near 100% water change as you can and that will give you a "clean" start, so to speak.
I'm sure the rock an everything is plenty cycled so no need to worry about a cycle starting or ammonia or anything. But definitely get it situated before any livestock. It sounds like your a ways off from even doing that so why even keep it running now. A year+ fallow is an awful long time for nothing....regardless of if they just wanted to keep it going.

 

[Aquamechanic]

Thanks for the replies.

It looks like draining it will be the best approach. I should get under all that rock anyway (dread) and vacuum up any settled sludge that accumulated over the few years it was set up. Unfortunately, nothing survived the freeze. Was hoping to give the client better news then a need for a fresh start but the benefits are definitely there.

I am starting up a RDSB on a 220 reef to see what results it will bring. Have read many threads including the never ending one but have seen very little hard data of peoples results in those threads. Also found the ATS idea to be very interesting and will consider a trial on another large system in the new year.