Overflow box questions

[mattcham]

I am planning to get an overflow box to use a sump filter on my 120 gallon tank which has no holes.

Reading Amazon.com reviews for overflow boxes, I have a couple concerns:

1. Will the setup result in a flood if the power goes out for 5 minutes?

2. Will the filter resume normally without human intervention when the power comes back on after a 5 minute power outage?

3. Anyone have recommendations for overflow box brands/models that would address the above two concerns? My budget is $300 just for the overflow box. I don't want to drill holes into the aquarium.

 

[Steve190]

I use the CPR overflow with a siphon pump on my 120 gal. Had the power go out twice and the sump caught the over flow of water from having no power and when it came back on it worked itself out and put the water back into the tank

 

[mr_X]

I don't have a ton of experience with HOB overflows, but the little I have leans me towards CPR boxes as well. I like the aqualifter pump as my assurance the siphon will restart again after a power outage. BTW, those aqualifter pumps wear out and should be changed every year or so.

 

[Dav3]

Aqua lifter pump is unnecessary if you match return pump to overflow appropriately. Unless you just want piece of mind. But as X said those pumps can fail too.

 

[Steve190]

Yes you do need the pump with the CPR overflow. It's the only way to keep the siphon. unless there is another way to keep the siphon that somebody knows about.

 

[Dav3]

Yes you do need the pump with the CPR overflow. It's the only way to keep the siphon. unless there is another way to keep the siphon that somebody knows about.

As I said. Correctly match the return pump to the overflow. Need to calculate flow of return line after headloss. If the flow entering siphon is too low then bubbles get trapped and don't get flushed out of the siphon tube. The build up of bubbles is what breaks siphon. Over size the pump then dial it back with a ball or gate valve.

 

[jeffaquarius]

This is what you need. At the drop down nav pick CS150 for the right size of your tank

CPR CS Overflow Boxes

You need to have an Aqua Lift pump connected to it permanently. Without it the siphon will gradually reduce due several things such as air bubbles, brown outs and what have you. You can prevent flooding by setting the normal level of sump so that there is enough space for extra water when brown out occurs. Another way is set nozzle of return just at the surface of water or drill a hole just a little below water surface so that backflow will not happen. Some use check valve at the return pipe.

 

[Dav3]

Again. Aqualifter is unnecessary. I don't use one. I never get air bubbles in my siphon tube. Siphon never breaks unless I break it manually.

 

[jeffaquarius]

Again. Aqualifter is unnecessary. I don't use one. I never get air bubbles in my siphon tube. Siphon never breaks unless I break it manually.

How do you prime your siphon without an Aqualifter pump?

 

[Dav3]

It's always primed. Even when power failure. Like last night. As long as you don't have air bubble buildup there is no issue.

Primed first time with a tube stuck up the back end. Never again.

 

[jeffaquarius]

I doubt it if you have ever used such overflow box. Your water will not just go up your tank and down to your sump. Your imagination will not work.

 

[Steve190]

It's always primed. Even when power failure. Like last night. As long as you don't have air bubble buildup there is no issue.

Primed first time with a tube stuck up the back end. Never again.

Post a pic of your overflow so I can see how your CPR box is set up

 

[jeffaquarius]

You know pretty well that once your overflow box is above water, the siphon will be gone. So every time you loose power or when doing pwc your box will be above water surface. You need to lift that water to start the siphon again.

 

[Sniperhank]

You know pretty well that once your overflow box is above water, the siphon will be gone. So every time you loose power or when doing pwc your box will be above water surface. You need to lift that water to start the siphon again.

When you are doing water changes, your water level won't drop below the overflow. The water level will drop in the sump.

I run a CPR overflow on my 55 reef. The aqualifter is a great assist as during the summer months I have many brownouts, causing my return to stop and start all the time. Has really screwed with things and the aqualifter really gives great piece of mind.

However, I use a paperclip to clean out the connections as algae and debris can get in there and gum things up. Nothing really too hard to do, just something I didn't plan for when first setting things up.

 

[jeffaquarius]

Im not sure how you do your pwc Mr Hank but a 10% volume removal of your water will surely drop your DT level appreciably and below your overflow box that it will stop siphon. Unless of course if your sump volume has extras of 10%. You can not remove water from sump if you have pods.

 

[Sniperhank]

So don't remove the whole 10% at once if it's a problem. I use my ato to refill and it makes it simple.

 

[Vdub99aml]

I ran this overflow box for several years. It incorporates a siphon break in the event of power loss, and features self starting for when power is regained. Other than routine cleaning/maintanance, the siphon break nipple needs to be periodically cleared because it gets clogged with salt creep which will reverse siphon your tank all the way down to the return nozzle. I believe this box is rated at 900 gph. http://www.marinedepot.com/Tom_Aqua..._Aquariums-Tom_Aquatics-OE1318-FIOFEB-vi.html

 

[mattcham]

Thanks for all the great tips. I'll get the CPR unit. It seems that people are in doubt of Dav3's self starting siphon with no lifter. He did mention the use of a ball valve mechanism. Maybe it kicks in to seal the intake when water level is lowering. That would be a genius contraption that might eliminate the need for a lifter unit.

Regarding CPR boxes: What would be the drawback in buying the largest capacity overflow model besides the price and aesthetics? I figure the largest unit will be less likely to clog and will need less maintenance.

 

[Dav3]

I don't have a cpr overflow but mine is mechanically identical.

Cpr has an airline nipple on top. Just attach a piece of airline tubing to that with a check valve on the end.

When tank water level drops below intake side of cpr overflow does the intake section drain out? Hole in bottom? If not them there should be no siphon loss.

 

[PB_Smith]

I doubt it if you have ever used such overflow box. Your water will not just go up your tank and down to your sump. Your imagination will not work.

No, the water level in the overflow box will only drop to the level of the strainer grate on the in-tank portion.
As was pointed out, you would only lose siphon if air were allowed to accumulate in the overflow "tube".
When the power goes out, the overflow should only drain the last section, not the entire thing, and it should maintain siphon. If you raised the black "divider" to a point that it was almost the same level as the last divider, you could lose siphon.
I's the balance between the black adjustable divider and the final section that determines if siphon is lost when the power goes out at least on the CPR model it appears to be how it works.

Look at the pic, you'll see what I mean.