Water feed position for a recirc skimmer?

[shelburn61]

All recirc skimmers seem to have the raw water input near the top of the body. I understand the countercurrent theory, but I'm wondering how much difference this really makes with a recirc pump?

I'm building a new skimmer and would like to avoid drilling unnecessary holes in the tube. Would performance suffer from having the feed plumbing tapped into the line for the recirc pump?

I threw together a basic mockup to illustrate what I'm talking about:


Recirc pump plumbed as usual. Raw water from overflow/feed pump enters at valve.

Thoughts?

[rivdog]

recirc turns it over many more times . slower feed.more circ

[shelburn61]

Originally posted by rivdog
recirc turns it over many more times . slower feed.more circ

??? This has nothing to do with my question.

I understand how a recirc skimmer works. My question is whether it is necessary to have the feed enter at the top of the reaction chamber?

[aninjaatemyshoe]

With the design you have, water from the feed pump can go two ways. It can either go into the pump to be pushed out into the skimmer body or it can go directly into the skimmer body. Problem with that is that the water that goes so low into the skimmer body may simply drain out before it ever really comes into contact with bubbles. I would say a rather small percentage of water will do so and most of it will go into the pump. However, this is less than an improvement from the regular counter-current design. I wouldn't really be able to tell you how much this design will impact performance, but my guess is that it would be minimal/probably not noticeable.

[Pbrown3701]

aninjaatem... - thats not true. all the water being supplied to the skimmer woudl go through the feed pump as there is suction at that point. water would not flow out of the recirc input unless the supply to the skimmer was under pressure.

Water would either flow in from the tank and from the recirc intake (desireable) OR if the supply was under more pressure, water would flow out of the recirc intake (undesireable). The second way, you don't have a recirculating skimmer anymore....you have 2 pumps in series supplying water to the skimmer.

Does this make sense?

ALso, i would introduce the bubbles from the recirc as low as possible to give them more contact time. Or at least angle the output from the recirc pump downward.

[shelburn61]

Right! All the feed water has to pass through the recirc pump before entering the skimmer.

Is this just as good as having it enter higher in the chamber?