Back flow prevention

[Young Frankenstein]

Would you install back flow prevention valves in the supply? Or it will restrict flow by much? Does anyone have them?

 

[adnup]

Some people use check valves. You can find them <a href="http://aquaticeco.resultspage.com/search?w=check+valve">here</a>

I just make sure there is enough room in my sump for the backflow of water.

 

[WaterKeeper]

It is a good idea to have check valves on any line that will be submerged or that can form a siphon if the pump shuts down. Yes, they do create head but in a sample system model using an Iwaki-40-RXT then adding a check valve the check only dropped the flow from 1021 gph to 999 gph. Not enough loss to be of concern. You can do the calculations yourself using The RC Head Loss Calculator

 

[Young Frankenstein]

Thanks adnup, waterkeeper

 

[Fuzzy Yarbles]

Check Valves are essential if you don't want a flooding sump.

 

[Salamander]

But what if your check valves fail. Like adnup and many others its easier just to allow room for back flow. Just don't plumb your system so that it'll siphin out all the water. Use a few strategically placed air holes to break siphon. Its simple.

 

[WaterKeeper]

True Salamander but what if the siphon break hole clogs? I like to see both systems used.

 

[Salamander]

The way I plumbed my drains only like 3-4 gallons drains. If the siphon break is clogged (there is more than one so...) it'll drain maybe 10 gallons max. I have enough room for either event.

 

[crumbletop]

<a href=showthread.php?s=&postid=9560305#post9560305 target=_blank>Originally posted</a> by Fuzzy Yarbles
Check Valves are essential if you don't want a flooding sump.

I recommend positioning one of the return openings near enough to the surface of the water so as to break the siphon before the sump overflows. That requires designing the sump baffles, etc, to accommodate the backflow. Check valves are unreliable, IMO. I think a small drilled "siphon break" would be similarly unreliable. Nothing wrong with having both methods (check valve + position of one of the return exits) -- but if you must have only one, the return exit method is the most reliable and failsafe, IMO.

As an example, one of the LFSs here in Nashville just got a way cool zero-edge coral tank that has the water pumped up from the inside and the water overflows the walls of the aquarium back down to the sump. Pics of the kind of tank from MACNA are below. As you can see from the pics, the only method for keeping all that water in the tank in the event of return pump failure, or a power outage is check valves. I.e. the check valves are the only thing between the pump and over 100 gallons of water. I recommended the folks at the LFS change the pipes on the inside of the aquarium to move the first outlet hole closer to the surface. In doing so, the max water that could drain would be from the top of the tank to the opening of the first hole. Check valves + plumbing are a must in this situation, IMO -- but the failsafe is the plumbing, not the check valve.

 

[AZDesertRat]

Keep the returns close to the surface and maintain freeboard space in the sump and neither drilled holes check valves are necessary. Drilled holes plug and check valves fail, positive air breaks do not.

 

[Young Frankenstein]

thanks I adjusted the supply and it works fine.

 

[michaeldaly]

I just use a siphon break whole just below the surface of the water on my return pipe. I clean the whole periodically and have never had any problems.

 

[AZDesertRat]

Just wait until one day you are away from home and you forgot to clean it. Why recommend a temporary solution or an afterthought for poor planning when they can do it right the first time and not have to drill any holes or add check valves. Lets start people out right the first time when they have a new system. If a person buys a used tank that is already drilled in such a way that correct design is not possible but if they are starting fresh do it right. Just my $0.02.