How do you figure the flow into the sump?

[TNT]

I am going to make a sump in the next few days out of a Rubbermaid container as I have seen on this site. I think it is a great idea and a great way to save some $. I am sure that this has been covered before and hope someone will bear with me. My question is how do you know what the flow out of the tank into the sump is? I am going to do this with PVC and then buy a pump to take the water back into the tank. I know that the pump rating will be diminished because it will have to pump the water about 4' back into the tank, but hopefully the pump will have a rating to tell me that info. Any help would be appreciated.

[ReefNeck]

Easy one. :)

If you get a 550GPH pump and say it loses 100GPH for the 4' head then you will be pumping about 450GPH. The overflow will drain to the sump at the same rate as the return pump. Most standard overflows are 600GPH max. Some duals up to 1200GPH. Don't get a 1200GPH pump with a 600GPH overflow or it will overpower the overflow and overflow the tank.

[TNT]

Thank you....I understand the rating on the pump...but my plan is to drill holes in some PVC pipe about 2" below my water line and start a suction there....the holes will stop the tank from overflowing into the sump by letting air into the pipe and breaking the suction in the event of a power outage....but I don't know what diameter PVC to go with and how to figure out how the rating on that works as far as the amount of water that will be coming from the pipe into the sump.

[ReefNeck]

The problem I see with that is that every time there is a power outage/surge it will break siphon. When the power comes back, Your pump will begin filling the tank but the PVC will not restart the siphon causing your tank to overflow.

If I am understanding what you want to do correctly.

Some type of overflow box is a must to prevent this.

Correct me if I am not clear on your intentions.

[TNT]

Actually I am going to use a power strip that will trip with an electric outage and has to be reset if anything like that happens so that the pump won't overflow the tank in that case.

[ReefNeck]

Being that this is a DIY type setup and well beyond my scope of doing things, (I like old school know you can count on it stuff) I will refer you to David who will probably chime in sometime today. He seems to be real good at this DIY stuff and may be able to help you figure out what you are trying to do. Personally, I would never want it that way. I want my return to restart in case I am away for more than a couple of hours.

My wife's family is over 1100 miles away and if we go visit it won't be just an overnight thing. lol

[dakar]

I think the magic numbers you are looking for about the flow are approx 500 gph max for 3/4" pvc and 900gph for 1".

Can scratch out a drawing of your proposed method for the overflow and post it? ... the plan I see from your description may have some major design flaws that can be remedied.

[TNT]

Thank you...that was what I was looking for....I will post what I am thinking in the next couple of hours....It is not as far our as what I think everyone thinks it is...just tired and not doing a very good job of telling everyone what the idea is.....lol

[TNT]

Ok....should have stated earlier that I am going with an overflow siphon into the sump and I was wanting to check the flow rates of per inch for PVC to make sure that I bought a big enough pump to push the water back up the back of the tank. The way I understand it I can either go with an air diffuser to pull air out of the siphon in case of a power loss or I have an old power strip made for our first big screen that has to be reset any time the power goes off. I have a 90 gallon tank so I want to flow about 600 gallons an hour and was trying to check what the guy at the LFS was telling me. Sorry to confuse everyone, but I have been looking for ways to add a sump at minimal cost w/o having to have my tank drilled.

[TNT]

Also, he is willing to build me one for $45.... From what I have seen that is reasonable, and he has a tank at his house that I have seen that is set up this way that seems to work well.

[ReefNeck]

Now that makes it clearer. :)

If you go with a U tube type overflow box they will not lose their siphon when power goes off. I unplug all of mine for maintenance all the time and when I plug them back in they start working.

The CPR style overflow requires a pump or powerhead to suck the air out of the tube to maintain a siphon. I personally do not use this type because they fail more often than the U tube types do.

If your overflow can handle 600 GPH then get a pump that can do 650 GPH and with the 4' lift you will come out close to maximum flow without problems.

I hope that helps, If not....I'll shut up and let someone else try. lol

[AquaSquid]

Make sure that you place a check valve between your pump and the tank. this will prevent siphoning and a major flood in case of power outages.