Calculating backflow?

[lowfi]

Alright, this topic dumbfounds me. How in the world do you calculate backflow of your system if there is a power failure? There is no way I can overflow my sump because I have people living underneath me. I dont even know where to begin with this question. Is it a function of your overflow box size? If anyone can help me out at all that would be sweet. Im going to be setting up a 50 gallon tank (36" long) with a 20L sump. I am still trying to figure out plumbing configurations and what pump to buy for my return. I think that I am going to be ordering the tank from AGA with the tank predrilled and overflow box(es) already assembled and attached. I will be running the ASM G-1 skimmer.

Thanks so much,
Sean

[BigAl07]

If I were doing it (and I will be in less than a WEEK hopefully) I would fill my Display Tank to Max normal height ( sump empty) and assuming you have a "siphon break" in your over flow box measure how much water flows from your tank into your sump before the siphon breaks. Add a little extra for errors and the should give you a good idea of what to allow for. Keep in mind this is ALL in theory as I am about to do my first one this week. I'm sure there are other ways of determining that.

[tbittner]

That is what I did. Do your best guesstament on water capacity. Then unplug the pump and keep an eagle eye on the water level in the sump. If it looks like it's going to overflow, plug the pump back in and the water level in the aquarium will rise back up, preventing an overflow.

Now you can remove some water, doesn't matter where from (display tank or sump) and retry your experiment until the water level in the sump is at an acceptable water level. This could mean that your guesstament was too low and you need to add more water to your system. Doesn't matter where you add the water.

[Woodstock]

To test the backflow needed: with all pumps on and running add just enough water in the sump to allow the return pump to operate; next turn off all pumps and wait about 15 min for the water to settle down into the sump; from this point you can see how many more inches of water can be added without overflowing the sump. Does that make sense??
Always heed the side of caution and keep extra space in the sump.

[DrHank]

Your tank is 36" long and 18" front to back. Each inch is about 2.8 gallons so all you need to know is how many inches your tanks water level drops with power off. My guess is about 2" of less so figure you need the capability of your sump to handle a back flow of about 6 gallons.

Here's how that's figured:Reef Central Online Community

[DrHank]

Your 20L will do fine. That's what I use on my 36" 65 gallon. Just don't overfill your sump initially.

[Scouter Steve]

With a reef ready tank, remove the durso's so the overflow never fills to top. Fill tank and let it overflow into sump with all heaters, skimmers, pumps etc. set in the sump. Allow skimmer body to fill to the same level of sump. Fill tank untill the sump is within an inch of overflowing. I do this with durso's out because in a long power outage water will empty from the overflow due to the fact I don't glue in return and durso inside the overflow. Once sump is full, replace durso's, start return pump and skimmer pump. Mark the level in the return section of the sump after 5-10 minutes of running where things have evened out. This would be the maximum level to keep your sump when running.

[mps9506]

Originally Posted by DrHank

Your tank is 36" long and 18" front to back. Each inch is about 2.8 gallons so all you need to know is how many inches your tanks water level drops with power off. My guess is about 2" of less so figure you need the capability of your sump to handle a back flow of about 6 gallons.

Here's how that's figured:Reef Central Online Community

Don't forget water in the plumbing and skimmer body that drains into the sump also. Good bet to add another gallon to that

[BigAl07]

Since I have mine built with cut-off valves at the bottom I'll do this:

Fill tank to max height close valves. Add volume of skimmer (not much but some) and then open both valves. Water will drain from main tank into sump area. Approximately 2" ( approx 7.5 gallons in my sump +plumbing) and I would now have an accurate measurement for how much comes OUT of the system during a power outage. Of course this is still THEORY and would have to be tested. Like mentioned above... leave MORE room than you calculate because water always expands beyond your calculations when people live below you. It's a proven fact.

[tbittner]

[sasquatch]

Originally Posted by Woodstock

To test the backflow needed: with all pumps on and running add just enough water in the sump to allow the return pump to operate; next turn off all pumps and wait about 15 min for the water to settle down into the sump; from this point you can see how many more inches of water can be added without overflowing the sump. Does that make sense??
Always heed the side of caution and keep extra space in the sump.

Tried and true Woody! I use a black marker on the sump to define Overfill lol, currently Im 10 gallons above my max line but my flood area is a designated wet zone

[Adam Black]

Hey can I see a few pics of the 65g tanks? I'm going to put one up and I would like to see one done already or in the making at least.thanks guys.


Adam

[DrHank]

Allen, you and Mike are such party poopers (even though you're right). I didn't take that into consideration but, if he runs his tank with his sump no more than half full, and his sump is 20 gallons, will it overflow? Not unless the water to the bottom of his bulkhead fitting, in his skimmer and his lines exceeds 10 gallons.

[lowfi]

oh my god...this is scary.

Hey doc, do you have a pic of that 20 gallon sump that I can see, maybe we can compare notes if we are running the same system..

[BigAl07]

Originally Posted by sasquatch

Tried and true Woody! I use a black marker on the sump to define Overfill lol, currently Im 10 gallons above my max line but my flood area is a designated wet zone

Only you Sas.. .only you... I think I saw a Special on you last night.. was late and I was channel flipping and they had some type of Sas special on.. unfortunately I fell asleep looking for you and I THINK I may have had dreams OF you

Originally Posted by DrHank

Allen, you and Mike are such party poopers (even though you're right). I didn't take that into consideration but, if he runs his tank with his sump no more than half full, and his sump is 20 gallons, will it overflow? Not unless the water to the bottom of his bulkhead fitting, in his skimmer and his lines exceeds 10 gallons.

Party pooper? awwww that hurts.
Heck I'm just "thinking out loud" here... yall are the pros.....