100% of Overflow through skimmer?

So, recently read a couple things that leads me to believe this is a good idea primarily on larger tanks. I'm curious though how exactly this would be plumbed into the system. So after first writing out like 10 questions i had i think it makes more sense to just delete those and ask two (well, maybe 3)...

1. Has anyone done this/thought about this? Thoughts on it?

2. How would it be plumbed into the system for both the input to the skimmer and the output back to the tank?

 

I'm assuming you'd hookup the overflow to the skimmer pump and let it pull the water itself?

 

Or just get a return pump that would match the GPH of your skimmer, then plumb the overflow directly to the skimmer intake. This would put all the water through the skimmer. And as long as the return pump matches it it should be able to handle it fine.

 

Yeah that's what I was thinking to but I would assume you would want the intake pretty low to avoid it ever running dry but then would you need the skimmer to be higher than the tank to avoid overflow? In which case gravity could just feed it back to the tank I suppose... Pretty sure there's a way to run it under the tank to. I would just be concerned about both running it dry or my return pump not being able to keep up.

 

If the only pump is on the return side wouldn't you need a air pump to initiate the skimming process? Or would the suction be enough to pull air into the air intake?

 

Skimming is affected by gph and dwell time. If you want to run 100% of your water through a skimmer, that's fine. You better be rich though. I always oversize skimmers beyond their ratings.....sometimes up to 25~40%. If you want to run everything through a skimmer, you need to drop down to a very small return pump and have all water circulation via powerheads in the display tank itself. I would oversize the skimmer by 300% and would also highly recommend that it's a recirculating skimmer.

 

hmm ok. If i ever did this i'd probably run a separate closed loop to aid in the flow. Probably still end up with some phs but yeah...

 

as for the skimmer i'd probably try to get one from a guy that builds them himself. He started up a co for them, not sure how far he's taken it but sounds like he's very helpful and will even mill the parts for you if you're throwing one together yourself... company is called Aquarium engineering. He's got an incredible 20,000 gallon tank build thread on another site, not sure if i'm aloud to specify another forum so i wont... He basically build and designed the whole thing himself. Absolutely amazing... anyway.

 

One of the solutions for this that may make life a little easier, use a herbie style drain and allow the secondary drain to feed the skimmer. You may not be able to get 100% of your overflow through the skimmer unless it is a huge skimmer, but maybe 1/3 or so would be good. Plus by doing this you will eliminate the need for a supply pump just for the skimmer. The only caviat to doing this feeding method is that you will have to invest in a recirculating skimmer. But that really isnt that bad of a deal.

 

First, I would be interested in why it seems like a good idea... I mean the things you heard.

There is no skimmer manufactureer that will tell you that a tank of X gallons needs to be cycled by the skimmer X times per hour. The only thing you will find is simply X skimmer is rated for X gallons.... yet they will all vary on how many gph they will process and how much air will be contacted.

This is purely a guess from me, but way back from fresh water days and under gravel filters.... you cycled the tank volume through the biological filter... so it became easy to say you need X "turnover rate" of your tank through the filter. Even others say back in the day, flow from return pumps and through wet dry filters were primary flows in the display tank... however, none of that is relavent today.

The bio filter in the reef tank is the Live Rock, and water is circulated in the display tank with powerheads. Closed loops and return pumps cost a lot of power and add a ton of heat to the system compared to power heads. Return pumps are a very poor way to circulate water in the DT.

Which leads us the the mechanical filter... the skimmer. What ever skimmer you have rated for what ever it is rated for will only process X GPH. Moving water to it from the DT at a 1:1 ratio, or 1:2, or 2:1, is completely irrelevant to what it can process. Saying that you want to move "100%" of your return flow through it has to accomplish something.

If your skimmer does 100 gph, and you move 400 gph through your sump... that 300 gph is only being circulated and not harming anything. In reallity, it is 300 gph of water you do not need to move and adds heat and uses power for no reason.

But if you want to move 100% of your return through your skimmer... well then now you need a skimmer that can do 400 gph... one basically 4 times the size you need for simple numbers argument. So you do that... but that skimmer will not remove 4 times what the other one will do... in fact, if your other skimmer was doing it's job well, it won't remove any more at all... there are some that believe in fact the 400 gph skimmer will remove less that the 100 gph skimmer, but that is debatable.... so what you are left with is a much more expensive skimmer moving more water than needed, adding more heat, needing a bigger sump.... all for no gain in filter capacity.

So then what to do... the same thing that should always be done... don't needlessly move water through your sump for no reason. Move the amount of water your skimmer will process and anything else you need to supply and that's it. I didn't do a 1:1, but within reason... 1:1.5. My skimmer processed so much, my fuge needed so much, a little extra for the heck of it... done.

I hope that helps.