overflow questions

[gallagherjim]

2 questions... first, i recently set up a cpr overflow. I recently read some bad reviews on these...can anyone be more specific on what to watch for.

Also, has anyone tried to put a sponge filter in the opening in the tank. It would keep critters out and also keep the box clean. My concern is that it may reduce the flow into the box. Any help?

Thanks

[captivereefs]

Problem is is that air can collect in the elbow of the overflow. You need to connect up a powerhead like a rio 800 RVT to suck the air out.There should be an air fitting on the top of the overflow elbow. If to much air is allowed to collect the siphon wil break and the overflow will stop working.

[captivereefs]

And do not put a sponge in the overflow box. It cabn cause decreased flow and siphon failure. Only use the sponges that come with the overflow.

[gallagherjim]

thanks, have this in place already, any advice on putting a sponge type prefilter in the box. When i feed the guys, some food gets sucked into the overflow and then just sits in there... this can't be good.

[captivereefs]

You can always shut the main pump off for feeding. I would strongly caution you not to put anything in the prefilter box to catch debris; that is a good way to empty your sump onto the floor if the flow through the box is reduced.

[gallagherjim]

will do.....already had a sump leak (30 gal overnight) not ready for that clean up again. thanks

[loganj]

Two points I'd like to make. First, if you shut off the main pump to feed, shut off the PH that is attached to the overflow as well. It can eventually empty the box and break the siphon...not a big deal as long as you notice it. But, if you didn't notice it and turned the pump back on...water on the floor. Second, and I think this is the first time I haven't agreed with Darin about something, I would not trust a Rio pump/powerhead for anything. I wouldn't use anything but a Maxi Jet 1200 on that overflow. It has enough flow to restart the siphon by itself and is one of the most reliable PH's available. If you need reliability anywhere, you need it on the overflow. JMHO.

[captivereefs]

The maxi is definately better. But on the CPR overflows the pump actually helps start the siphon so leaving it on should not hurt anyting. The iinstructions that come with the overflow actually tell you to start the siphon by letting the pump run. There is water on both sides of the elbow so it willl act like a vaccum sucking all the air out and drawing in water.

[loganj]

I should point out, and I'm not trying to be difficult, that the very action of starting the siphon is what will eventually empty the box. When you shut off the main pump, the water level in the tank will drop until water is no longer flowing into the internal box. At that point, if the powerhead is still running, it will slowly draw water out of the U tube through its venturi until either the main circulation pump is restarted or the water in the overflow box runs out. At that point the siphon breaks. The PH won't restart the siphon before the main pump runs the tank over...unless you have a relatively small pump. Yes...I learned this the hard way .

[captivereefs]

No sweat, did'nt think you were trying to be difficult! Different opinions are what make the boards so informative!

[nguyen27]

I think LoganJ and CaptivedReef need to settle this in real life, bring all your merchandise out and let see who sell the stuff cheaper? We will be the judge for that!!!

[Crawling68]

I used to use an AquaClear 401 on my overflow, and it never drained. I know most people do not like AC powerheads, but ive used them for 10+ years and loved them. Ive actually left it off for hours and never drained it. The air intake is just strong enough to pull the air out, but kinda gives up when it starts pulling water. I now have a aqualifter pump on the overflow because i use a closed loop.