overflow box on a closed loop?

[vancelyndon]

i've searched forums and couldnt find anything about this... was wondering is it possible to use a siphon overflow box to feed a closed loop recirculation pump? i was wanting to do this to avoid drilling the back of the tank. i was planning on doing this as a secondary means of water flow....i was going to do another siphon overflow box to feed a sump and return pump.

i was looking at the cpr c siphon overflows and maybe a mag pump to drive a scwd with the plumbing coming over the back of the tank and into the water a few inches...does anyone have any experience with a similar set-up or foresee any problems? thanks

 

[woz9683]

Why don't you just set it up as a true siphon? Input straight over the back of the tank and output done the same way. In case of a power outage the water doesn't leave the loop so you don't have the possibility of running the pump dry or a flood when power returns. And you don't really want your closed loop to skim the surface either, and most of the overflow boxes do.

 

[vancelyndon]

ok guess i didnt think of that. i've never used an overflow box b/c my 90 gal was drilled with an internal overflow. this is going on a 80 euro that is already drilled but has no internal overflow boxes and i'd rather just plug the holes and not have an internal box take up so much space.

If i were to use a true siphon would with just a pvc pipe put underwater then running directly to the pump would i have a problem getting the prime started the first time or after doing a water change with the level dropping below the two outputs of the closed loop?

thanks for the help

 

[woz9683]

Wait, I thought we were just talking about the closed loop. You're still going to use a siphon overflow box for the drain to the sump, right? That should have an internal box that you do need for surface skimming.

The pump should stay primed even when you do a water change as long as you locate the pump and the inlet below the level you intend to drop. So, I'd sit the pump on the same level with the bottom of the tank, and do the inlet as far down inside the tank as you can.

But, priming the pump is easy. Just take a little pump/powerhead like a maxijet or quiet one, turn it on and put its outlet up to the CL inlet. That should fill it no problem. You might want to leave it there for just a couple seconds while you turn on the CL pump, just to make sure it's filled completely.

 

[vancelyndon]

michael-
yeah im still planning on using an siphon overflow box to drain down to the sump. thanks for the help. now my only concern is the inlet for the cl pump, im concerned it would be more prone to suck an anemone against it...more so than a siphon overflow would.

also just wondering but in your first reply you said i wouldnt want the cl system to skim the surface of the water. whats the downside to this? thanks again

 

[woz9683]

In order to keep something like an anemone from getting sucked into the inlet just put a T on the inlet with strainers on either side. Even if the anemone crawls over one side of the T the other side should pull enough water to keep the anemone from getting stuck.

Well, the whole reason for surface skimming is so that all the crap that collects on the surface of the water gets sucked down to the sump so the water getting processed by your skimmer, etc. is the dirtiest water possible. If you skim the surface with a CL, you just keep recirculating that gunk off the water's surface. So, it takes longer for the particles to make their way down to the sump and get processed. Not really a critical concern, just not ideal.