Overflow/return pump question

[JenkinsThePole]

So I yet again may have screwed up. After reading some reviews online and seeing a few other people go with the PF-800 overflow by eshopps for their 40b I decided to get one. Looking at it now its pretty beefy and I wanted to run my sump at about 300gph (the BMS Curve 5 skimmer can do about 260gph from what I read). I also went with a DCP 5000 pump from jebao figuring I could turn it down if needed. My problem is I'm worried I won't be able to get the stream through the u-tube going fast enough at only 300 gph which could mean air bubbles and then a siphon break. I could go with the pf-300 but I feel like its better to be a little under than running the overflow to its max. My main question is should I send it back and get a smaller one or keep the pf-800? (also feel free to critique my equipment I havent used it yet so I can still send it back if I messed up) It'll be on a 40b with a 20L sump.

 

[Pet Detective]

That overflow box is only slightly bigger than you need, but it will work fine, I'm not understanding your concern...300gph will be plenty fast enough to keep the siphon going, plus all you really need to do is adjust the box level a little lower so that more water flows into it....I've used a J tube & siphon for over 25 years.....I've NEVER seen a siphon be broken, physics are in play here, if there were 2 J tubes in 1 overflow, perhaps 1 might stop working but never both of them.

 

[JohnZena]

So I yet again may have screwed up. After reading some reviews online and seeing a few other people go with the PF-800 overflow by eshopps for their 40b I decided to get one. Looking at it now its pretty beefy and I wanted to run my sump at about 300gph (the BMS Curve 5 skimmer can do about 260gph from what I read). I also went with a DCP 5000 pump from jebao figuring I could turn it down if needed. My problem is I'm worried I won't be able to get the stream through the u-tube going fast enough at only 300 gph which could mean air bubbles and then a siphon break. I could go with the pf-300 but I feel like its better to be a little under than running the overflow to its max. My main question is should I send it back and get a smaller one or keep the pf-800? (also feel free to critique my equipment I havent used it yet so I can still send it back if I messed up) It'll be on a 40b with a 20L sump.

I agree. You should be fine. I would run 2 tubes siphons. Im not sure if it comes with one or two but 2 is safer and more efficient.

Sent from my LGMP450 using Tapatalk

 

[on the spot]

Two U tubes is not a good idea @ low volumes. that's exactly what causes air to be trapped in the first place. A single tube will be more than enough to keep that flow -

If you can get a hold of a smaller diameter U tube the better. You have 1" now? Velocity increases in a smaller tube.

and lowering the "box" only changes the tank level. Doesn't change the amount. Only the pump does that.

HTH