Fish tank hydraulics questions (O.T., but relevant?)

Ron Schroeder

Its been a long time over twenty years since my last Aquarium

David Minehart

Fish tank hydraulics questions (O.T., but relevant?)

My daughter has a large freshwater tank awash with floating algae. She's picked up a UV Sterilizer that'll kill the green monsters. However, it wants a flow rate of 120 gph for effective operation. The existing pump for the tank's aeration produces 350 gph. The UV sterilizer uses 1/2" id tubing, while the pump uses 3/4". My thought was to put a smaller diversionary circuit between pump and tank, using smaller tubing as needed by the UV device, so the pump's output would be divided into two parts. Smaller part would go through the UV device to the tank, larger part directly to the tank as before.

Questions:
1) Assuming T connectors before and after the branch, with step-down converters taking tubing size up and down as needed, would we still get the 350 gph? Or would the total flow drop? Or would flow stay the same but work the pump harder?
2) Assuming the areas of the tubing are, say, about 0.14*pi sq in (existing) to 0.06*pi sq in (branch through the UV device), would about 6/20 or 30% of the flow be going through the UV?

Ron Schroeder

Depends

on the pressure loss of the sterilizer vs pressure at the bypass may need a globe valve to get the flow right, you might find a vinal hose clamp ie medical supply place that will slow flow out the bypass. it goes over the vinal and squeezes it shut used on IV bags

LarryC

Pump flow

I suspect the pump's flow rate is probably under some specified non real world condition. Actual flow is probably less.

Like you said, Tee it close to the pump, take the straight thru path to the UV unit and pipe the remainder back to the tank. A regular adjustable screw hose clamp around the plastic hose would probably work fine as a throttle. Dump the discharge of the UV unit into a clean container and measure the time to fill one gallon. 30 seconds and you are set.

If you have to lower the flow thru the UV unit, throttle on the discharge.

To answer your questions, total flow will probably drop, yes the pump will work harder, and no the flow will not divide according to pipe diameter.

Larry

Unknown

why not

Why not throw some algee sucking cat fish? May take awhile but will keep the water cleaner and more fishes to look at.. Beats watching the clock moves....

Ron Schroeder

Algea eatting fish work great on

glass but do they do as good on that floating stuff??

David Minehart

Good question, Bruce. And the answer is, No. At least not fast enough to make any difference. The waterborne algae reproduce like you wouldn't believe. In a couple days, the 125 gallons looks like GatorAde, with visibility limited to about 3 inches.

Weezbo

Pond Lilies....

Ron Schroeder

I really didn't think so, but

have you tried adding saesalt to your tank, I forget but something like a tablespoon to 50 gallons, it helps keep down on disese and algea out burts on those critters and plants that don't like the ocean, make sure you get the stuff at the fish store. doesn't always eliminate but sure slows it down.

Unknown

salt

yes salt does work for a whole host of aquarium difficulties. i've used it with great success if the fish are not doing well for whatever reason. 1 teaspoon per gallon is the reccomended dosage. use only aquarium salt from a pet store or natural sea salt from a health food store.