Recirculating Skimmer flow question

[Jason72]

Hi all,

I'm looking at upgrading to a recirculating skimmer, but I'm confused by one aspect of them. They say that they need a flow of 1 to 1.5x/tank size per hour. Is that "suggested" or is that "required?"

The reason I'm asking is that I'm wondering about plumbing directly from my overflow. If I had a skimmer that was rated for up to 350gallons, could it handle being dirctly plumbed from the overflow at 600gph? Should a recirculating skimmer ALWAYS be T'd off?

Still an idiot, and hoping you guys can chime in

Thanks
Jason

 

[marine mike]

I would call that rate a generally accepted amount for optimum performance. I think the t thing is probably the best way to go when feeding from an overflow, some people find the skimmer handles it fine, others it is just too much too fast. The t allows you to pull some out of the feed to reduce that gph from the overflow. Unless your skimmer is huge, you will probably need to pull some out and reduce the gph to get optimum results.

 

[Jason72]

Thanks for the reply - I was thinking 600gph might be a bit much, but I' really sort of at a loss with a lot of this stuff lol

 

[Jason72]

And related... are recirculating skimmers really that much better than traditional "in-sump" designs? If a skimmer is only getting a portion of water to it anyway (because a recirculating one would be T'd off) - would a more economical choice be to go with a similar-sized in-sump skimmer?

Or am I missing an important component?

 

[Jim Tansey]

Not sure what you mean by "in sump design", most recirculating skimmers are placed in sumps?

Jim

 

[jrmx635]

skimmer

yes the recirc is way better.
there are a few reasons
one, in most cases it creates less pressure on the pump allowing for more flow into the body.
two,because you are feeding it from a drain,all water coming from your tank is being skimmed and not just a portion of it.
three,the water inside the skimmer body is being skimmed for a longer time,more contact time for bubbles.
example...think of it this way,if your skimmer pump is 600gph non recirculating and after the pressure of pumping inot the skimmer with air it is 300gph.
then your skimmer flow is 300gph.
if you recirculate it then you may be at say 400gph,but inside the skimmer only and your flow from the drain is 150gph,then your contact time is doubled and you have a flow of 150gph but the air of 400gph.
I am real bad at explaing in a rush so maybe someone can help explain better but thats the idea.

 

[Jason72]

By "in sump" I guess I mean the recirculatings are listed always as "in sump or external" whereas some are listed as "in sump only" (non-recirculating).

But jrmx... I think I get what you mean. Even if you T off the plumbing, the water that is in the skimmer will be better skimmed before it is pushed out - more contact time with bubbles, and so on.

I was planning on the octopus ddnw-150 - it's rated for up to 350 gallons. So yeah - I'd probably want to T off the overflow plumbing to better control that right?

Thanks again all
Jason

 

[stingythingy45]

Jason,

Basically all a recirculating skimmer does is keeps taking a portion of water from the body of the skimmer and sends it back through the venturi to be mixed with air again(more contact).
So yes,there is a ton more contact of bubbles with the water to be skimmed.
In my case it was taking the pump that used to feed the skimmer via sump water.Looping it so it just keeps taking water from the skimmer body and mixing it with bubbles via the venturi over and over and over again.Another hole was drilled for the overflow from the tank to feed it.

A recirc is basically taking water from the skimmer body and saying"I'm not done with you yet"and sending it back through the grind again(venturi).