Overflow Question

[Maverick00]

Hey guys, Im going to get a CPR overflow box for my 33 gallon im just not sure which model i should get. Im going to have a sump in the neighborhood of around 20-30 gallons. My question is which model (GPH) should i get for this setup? I plan on eventually upgrading my display tank to 50 gallons in the future and dont want to have to buy a larger overflow. thanks for any advice

[The Grizz]

If you are planning on an upgrade I would go with the one that is rated for 1200 gph, you can easily control your flow with a couple gate valves.

Depending on how much flow you are looking for go with a CS 102 or bigger.

[Maverick00]

thanks Grizz (i just saw your shallow tank build thread the other day, very impressive! The day i can afford a house on this god damn island I want to try a long shallow tank myself) im alittle confused as to how this all works apparently. Doesnt the overflow automatically adjust to whatever return pump i run as long as the overflow can handle the GPH rating of the pump? im not sure where the gate valves would come into play?

[fishytime]

I take it drilling the tank is not an option?

[The Grizz]

With a CPR overflow box do not exceed the flow rating of the box with a bigger pump, it will literally overflow. As for the gate valves they go in the line going to the sump, just above the sump. This will help you control the level in the box so you don't get that sucking noise. Also if you go with a CS 102 that is rated for 1200 gph and a pump that is only rated for 900 gph you will need a gate valve to slow down the flow form the box to the sump in order for the pump to keep up.

Hope that makes sense.

[axe_man16]

I would not get a CPR type overflow. They are dependant on a pump to keep them working. Although not 100% foolproof a u-tube overflow design is much better. I have never had a problem with mine.

[Maverick00]

that was actually the original plan, however it was a used tank and im unsure what kind of glass im working with. I havent a clue how to 'test' whether or not the back is tempered or able to be drilled. Another problem is i dont have a temp tank i could move everything to in order to drill, i assumed drilling with livestock in the tank would be.. well not recommended to say the least. Looking at the prices of the higher gph cpr overflows im wondering if upgrade time for the tank with panes im able to drill might be the cheaper and better way to go in the long run...

[axe_man16]

To test if your tank is tempered, you will need polarized sunglasses, and a source of light. A laptop or better yet the sun. When you put the glasses on and tilt your head the pane shows stress marks nd gets darker (if tempered).

[Maverick00]

Originally Posted by The Grizz

With a CPR overflow box do not exceed the flow rating of the box with a bigger pump, it will literally overflow. As for the gate valves they go in the line going to the sump, just above the sump. This will help you control the level in the box so you don't get that sucking noise. Also if you go with a CS 102 that is rated for 1200 gph and a pump that is only rated for 900 gph you will need a gate valve to slow down the flow form the box to the sump in order for the pump to keep up.

Hope that makes sense.

yeah that makes sense, thanks, the more i thought about it thats what i figured you meant.


@axe_man16 - Ive read numerous threads on various forums debating these two overflows which actually confused me even more. Ive read that even u tube setups can eventually have an air bubble buildup causing them to fail? Even if the airpump on the cpr failed wouldnt you have time to notice a slight air build up between the siphon?

[Maverick00]

Originally Posted by axe_man16

To test if your tank is tempered, you will need polarized sunglasses, and a source of light. A laptop or better yet the sun. When you put the glasses on and tilt your head the pane shows stress marks nd gets darker (if tempered).

ill give that a shot tomorrow!