Reducing the flow of a pump

[JRagg]

I have a question about how to lower the flow on my HOB filter. I originally had a TopFin brand one that came with the tank, but it died after less than two months. I decided not to risk failure again and I bought a better brand. It is a penguin that takes the “rite size B” cartridge, so that tells me it is a 125 ish gph pump. I thought that it was a 100gph, but I bought this about three years ago and no longer have the box. In any case I need to lower the flowrate coming out of it. I’m going with a planted 10 gallon aquarium and by the 5x tank size flowrate thumbrule I need to drop the capacity of the pump by about ½. I know some of the larger emperor filters allow you to raise up the inlet tube some which lowers the flowrate, but this one doesn’t have that option. I would rather not spend another $20 on a new lower flow filter if I don’t have to.

So I was thinking of ideas as to how I could make this pump pump less water. I’ve come up with a few ideas so far, some of which are probably excessive:

Block off some of the suction: This could be bad since I may end up with a cavitating pump. That would break my pump (over time) and be very noisy.
Block off some of the discharge: I would have to get something to put near the exit of the impeller to do this. I’m thinking a piece of plastic and some epoxy could do the trick… or for that matter maybe just a buildup of epoxy.
Redirect some of the discharge: Have some sort of hose that takes water from the discharge of the pump and redirects it to the suction. I’m not sure how effective this would be, and it would probably be a waste of time (eg. too much time to accomplish and added cost).

These are just ideas, and I’m sure that someone has had to do this before, so any help on this would be greatly appreciated.

Right now I’m leaning towards the epoxy method due to cost and ease of accomplishment.

 

[tbonem91]

personally, I would get a smaller filter.

that way, when you get another tank, you already have a filter for it

 

[JRagg]

My next tank will be a 55 gallon at least (last big one was a 45), so this filter won't be adequate. This is one of the smallest filters that penguin makes and the smaller one is still twice as big as I need. I'm on a very tight budget getting this set up again (getting married in 3 months), so I'm taking any chance I can to save money.

I'd rather spend the $15-20 that a new filter would cost on something else like a better test kit or some extra plants. That and I figure if this is something that someone has done before then I may be able to get some good pointers on what works best.

 

[sir_dudeguy]

is there any way to raise the intake tube? i know that on some hob filters you can raise the tube and it slows it down.

 

[JRagg]

The larger one that I had with my 45 gallon had that option, but this one has a cover that goes over the intake tube, which makes it to where it can’t be raised. I guess I could pull off the cover and see if raising it works. If it does I guess I could just trim up the cover with a dremmel or something to allow the tube to raise with the cover on.

 

[jsoong]

I have not try slowing down a HOB, but I can generalize from sump pumps ....

Generally it is not good to block off a pump to reduce flow. This put stress on the pump & shorten its life.

Redirecting the outflow ... easy to do in a sump set up, but pretty impractical in a HOB.

You can increase the head height the pump have to work against. Since raising the intake tube is not an option, you can raise the whole filter. If you can somehow shim the filter up a couple inches, that should be the same as raising the intake tube. Of course the outflow would now be higher so there would be issues with splashing & noise. But then, it is pretty easy to just put the HOB on blocks to see how it works for you before you make any permanant changes.

One other thought - Why slow down the flow? I am all for over-filtration (having goldies and all .... my 10 gal QT uses a 250ghp HOT Magnum ). Unless you are doing CO2 injection, having higher flow rate shouldn't hurt, even for a planted tank.