wet/dry advice for an idiot

[bbortko]

I have a 20g tank that is going to be upgraded to a 36g bow front(unless I can convince the warden that a 55 makes more sense since they cost the same), I already have a 10g hospital/quarantine, and I'm only allowed 2 tanks until I buy a bigger house. Since I'm about to have an extra 20g that I can't set-up I've been tossing around the idea of a diy wet/dry with a cpr overflow box. The 125 has 2 fluval 405s and the wet/dry would either run in conjuction with the 2 or replace one depending on stand space. Can someone clarify the risks of overflow due to the pump stopping either from power loss or mechanical issues.

 

[bbortko]

One more question. See lots of charts for pipe/tube sizes and their flow rates, however I am having trouble finding filter size to flow rate info. I am looking at 300 and 600gph overflow boxes, preferably six but dont know if thats doable in a 20g wet/dry. Is their a rule of thumb for this or just make sure the over flow and pump are of compatible rates.

 

[ruddybop]

One more question. See lots of charts for pipe/tube sizes and their flow rates, however I am having trouble finding filter size to flow rate info. I am looking at 300 and 600gph overflow boxes, preferably six but dont know if thats doable in a 20g wet/dry. Is their a rule of thumb for this or just make sure the over flow and pump are of compatible rates.

That is why you have a ball valve on the overflow and pump so you can adjust the flow input rate or overflow rate......If you have a 600 gph overflow and a 1000gph pump you can turn down the pump flow so the overflow matches the Pump(also look at the length of the output hose and heidth(the pump pushes less GPH the higher the hose is...The back of the box of the pump will explain GPH rate) Hope this helps ...

 

[prober]

You want your overflow to be able to flow more water than the return pump. If it does not you could throttle down the pump as mentioned above but then you are wasting some energy and could have bought a smaller pump.

You need to figure out how many times an hour you want to turn over the water in the tank. With a 125 I would go for 6 times an hour. That means that you need a pump that will flow 750 GPH at 4', assuming the top of the tank is 4' above the sump. The hight it must pump up to reach the display is called "head" so for this example the pump must be capable of 750 GPH at 4' of head. In that instance you will need an overflow capable of at least 800 GPH. I would do 2 600 GPH units for added safety. That leaves some room for partial blockages without flooding.

As for power failures, once the pump stops there will be no more water entering the sump from the overflow. It can only overflow what is pumped into it. That means all you have to worry about is the water in the return hose. A simle hole drilled above the water line of the display tank is all that is needed to break the syphen. Just drill it pointing into the tank and when the power fails it will suck air and not water. You will have a couple gallons in that return hose that will flow back into the sump but sumps are usually not very full so there should be plenty of room.