Quick sump question

[colin779]

Does having the drain line below the water level in the sump slow down the amount of water my HOB overflow can remove from the tank?

 

[poakley723]

It may change the maximun water flow your overflow can handle. That would probably have to be tested with diffrent pumbs but I do know that the water flowing through your overflow is determined by your return pump. How ever much water is pumped into your tank will flow back down. Probably didn't answer your question but its what I know.

 

[colin779]

The Hang on overflow is supposed to be able to take 800gph, my return pump can pump 750gph, but if i close off the T so that all of the water is going up the return to the tank, it will flood the tank. And it will flood fast, im guessing the overflow can only take about 400-450 tops. I'm a little confused how they can rate it at what they did...

 

[menace78]

The Hang on overflow is supposed to be able to take 800gph, my return pump can pump 750gph, but if i close off the T so that all of the water is going up the return to the tank, it will flood the tank. And it will flood fast, im guessing the overflow can only take about 400-450 tops. I'm a little confused how they can rate it at what they did...

What size bulkhead is in the overflow box and how many bends are in the drain line back to the sump?
Both of these things can effect how many GPH an overflow can handle.
Most HOB overflows I know of have a single 1" bulkhead whitch at max can handle only about 700gph, and that's only under a full syphon. every bend in that drain down to you'r sump will decrease this even more.

If you have room in the overflow, you could always add another bulkhead as long as the part that brings the water over the rim of the tank can handle the flow.
hope this helps a little.

 

[colin779]

The drain line has 2 45's in it, (the line is 1" pvc), im thinking tomorrow i will get a little more 1 inch and try to eliminate one of the 45's.

 

[menace78]

The drain line has 2 45's in it, (the line is 1" pvc), im thinking tomorrow i will get a little more 1 inch and try to eliminate one of the 45's.

You can also replace the PVC with flexable spa tubing. that would eliminate both 45° bends, but I would guess that a single 1" bulkhead will top out at about 600gph no matter how you plump it.

When you open up the return all the way and the tank goes to overflow, does the outside portion of you'r overflow box fill up just as fast or is the water in the tank noticibly higher?
and what kind of HOB overflow are you using?
I got a CPR90 to tqake 1800GPH with some modding, so there's hope for you'r overflow box if you don't want to add another.

 

[colin779]

The water in the tank will rise above the entire overflow box if i let the pump go at full flow. I don't think the level of the box outside the tank changes...

I have a eshopps pf 800, it is allegedly rated at 800gph... I didnt make it to the store today to get some more pvc, but i should be able to tomorrow. I can't imagine one 45 would do to much to slow it down?

 

[braddo]

The water in the tank will rise above the entire overflow box if i let the pump go at full flow. I don't think the level of the box outside the tank changes...

I have a eshopps pf 800, it is allegedly rated at 800gph... I didnt make it to the store today to get some more pvc, but i should be able to tomorrow. I can't imagine one 45 would do to much to slow it down?

Like Menace asked, is it a perfect siphon, is any air being sucked down the drain pipe? Air can slow the water flow quite a bit.

 

[menace78]

The water in the tank will rise above the entire overflow box if i let the pump go at full flow. I don't think the level of the box outside the tank changes...

I have a eshopps pf 800, it is allegedly rated at 800gph... I didnt make it to the store today to get some more pvc, but i should be able to tomorrow. I can't imagine one 45 would do to much to slow it down?

I just did some googling and It looks like that overflow hase been noted by many people not te even be able to handle a mag7 pump with 4' of head on it.

If you have no air bubbles in the Utube and have a good siphon there, than it's just not handleing the flow.

seen 3 different people state throttling back a mag 7 to 2/3 power with a ball valve was needed with this overflow.

sounds to me like the rating on that is overstated.
I would asume maybe 400-500gph max with that overflow.

Sorry but I hope this helps.
On a side note people have been modding these with extra Utubes and dorso's to quiet them. most people complain that there VERY loud.

If getting another one I would suggest a CPR style one. I had the CPR CS90 rated at 600gph (under rated IMO) and was running a mag18 at 2/3 throttle with 6' of head and it was both quiet and reliable (with the luft pump)

P.S. You'r drain piping is not the problem. it's the overflow its self if the tank rises above the outer section of the overflow box. you'r plumbing can't drain any quicker than the box can get the water over the side of you'r tank to th3e bulkhead that all that plumbing is atached to..

 

[KrautBurner]

maybe just add a 2nd overflow box, should be easy enough.

 

[mfinn]

I would get a smaller return pump.
You only need 3X to 5X tank volume going through the sump anyway.

 

[jrgilles]

Do you have any modifications on the bulkhead? A strainer or something will cut the flow way down...

You could always add a second overflow box, and do a herbie style drain. Runs silent, and then you also have a backup going incase the main drain clogs. Could put a bigger bulkhead on the second drain as a precaution, or get an overflow box that is rated higher. I'm using an eheim 1262 and overflow boxes from ebay that can each handle the flow easy

 

[Scooterman]

I would get a smaller return pump.
You only need 3X to 5X tank volume going through the sump anyway.

This is a good alternative IMO!
If your stuck on re-plumbing (excuse me I didn't read the entire post) I'd go bigger like 1 1/4" to ease up on restrictions. Even if you have to reduce it at the ends.