Red Sea (XXL750) Overflow Question

[ariellemermaid]

TLDR: On vacation, and I have reason to believe my overflow grates are clogging up. Can anyone tell me on the Red Sea overflow box what happens next? Would the tank overflow, or can the box accept water from the top around the lid?

The long version is that our tank is a wreck after the hurricane. The balance in the tank got thrown off with tang deaths, and now there’s a crazy amount of algae and cyano. So every 1-2 weeks I’ve had to clean the overflow grates. We’re moving soon though, and the plan is to reset the tank. In the mean time, I just need it to not create a disaster.

The ebb and flow of the tank is that I first get a sump “high” alarm, and then a day later I get an ATO runtime alarm (essentially, a sump low alarm). I’m actually not sure why the sump level goes high first, but this has happened before. In the past, before I recognized what’s happening, I have manually activated the ATO to get the sump level correct. However, this pushes the tank level to the point it’ll actually contact some of the screen top.

We’ll be home in 3 days. So I think my options are to just leave the ATO off for 3 days (probably the safest option), fill the sump and hope the tank will act as it has in the past since it’s never overflowed, or perhaps I should just turn down my return rate? What do you think?

 

[Hemmbone20]

I’m confused, is there livestock in the tank? If you’re worried about it overflowing I’d definitely turn the ATO off.
Can somebody go check on it for you?

 

[ariellemermaid]

I’m confused, is there livestock in the tank? If you’re worried about it overflowing I’d definitely turn the ATO off.
Can somebody go check on it for you?

Yeah our inverts, clowns, damsels, goby’s etc. all survived along with corals. No, we don’t really have anyone that can check on the tank. I’m leaning towards turning down the flow so it balances with the current state of the overflow better; currently running 2 Sicce’s at 50% each.

 

[IceNein]

It sounds to me like you have an extremely light bioload on a 160 gallon tank. A couple of clowns, some gobies and damsels? I would consider turning off your return pump completely and leaving your powerheads running.

The concern with water turnover is oxygenation, but I can't imagine that such a small bioload would be able to suck the oxygen out of the water faster than it could diffuse though the surface.

Well, I guess there's the issue of heating too, but what temperature do you keep your house at?

 

[ariellemermaid]

It sounds to me like you have an extremely light bioload on a 160 gallon tank. A couple of clowns, some gobies and damsels? I would consider turning off your return pump completely and leaving your powerheads running.

The concern with water turnover is oxygenation, but I can't imagine that such a small bioload would be able to suck the oxygen out of the water faster than it could diffuse though the surface.

Well, I guess there's the issue of heating too, but what temperature do you keep your house at?

That is an option; upstairs is currently at 65 though. I’d be a little worried about biomass in the sump dying from lack of oxygen too.

Update: I tried going down to 40% on both pumps and now have a sump high alarm. It’s the Neptune ATK so there’s only about an inch between the fill and high sensors. Plus the sump can’t overflow, so I think this’ll work for now.

I do still wonder what would happen if the grates clog completely or near completely. Would the lid allow (enough) water around it, would the lid float off the overflow box? Surly Red Sea has thought about that. Might have to experiment when I get home, maybe block the grates with a bag or something. Emergency overflow doesn’t do much good if the water can’t get to it.

 

[UncommonSense]

can the box accept water from the top around the lid?

I just checked the lid on my Reefer overflow box; it’s a pretty snug fit, but doesn’t overlap the sides of the overflow box…. I’d say it’s good for a trickle of drainage; 150-200gph max… it’s also ~1/2” below the rim of the tank!