Preventing sump overflow

I've read a lot of posts regarding insufficient sump capacity in case of a power outage, and the resulting flood from the return line siphoning back into the sump. The usual idea is to drill a small hole in the return line right below water level to break the siphon, and this is what I've always done. Some even drill two holes in case one gets plugged. I've always thought about a check valve in line above the return pump, but all I could find contained metal springs, so they were out. I recently found these CHECK VALVES and ordered the 0821-10C and installed it a couple of days ago. Totally plastic, comes apart for easy cleaning, and CHEAP. I had my system kinda running "on the edge", as when I shut down the return pump, the sump would fill almost right to the very top. It wouldn't actually flood, but got full enough to make me nervous. Now, with the swing valve, I can shut everything down, and still have the sump level 3" below the top of the sump because there's virtually zero drain back. It was the best 20 bucks I've spent in a long time!

 

The reason most opt to drill a hole rather than use a check valve is that a hole doesn't obstruct flow and catch any particles. Over time a check vlave will fail. sure you can take it apart and clean it but that's adding one more chore to our list of maintenance and with most people, over time we get lazy and it gets over looked. If you are willing to keep up the maintenance, you should be okay, but there is always that risk of some large particle getting sucked up and pumped through and failure occurring. Swing cecks only require a piece to get wedged in the plate and they are stuck open. I do piping for a living and we run into this all the time. For me I have a 90 on the end of my return and it is slightly above the water, so I have 0 gravity feed of tank water when power goes off. But to each is own.

 

+1 to this. I use 3/16" holes since 1/8" plugged. I also use the 2 holes on the return also.

 

Yep, to each his own, but I like these valves. You'd have to be passing large chunks of crap via your return pump (probably wouldn't make it without stopping the pump) to "stick" one of these open. They really won't require much maintenance unless you have a light shining on them causing algae to grow inside. I think they are an excellent "back up" in case your anti-siphon holes clog, etc.

I'm not trying to be cocky in any way, but as far as doing "piping for a living"....well I have about 25 years experience in agricultural irrigation. My last project was designing and installing a computerized irrigation system on a 1300 acre Orange grove in Lake Alfred Florida. The tricky part of that system was filtering waste water (NASTY!!!) from the processing plant coming at me for 7 miles through a 14" main @ 2500-2800gpm, and cleaning it up enough to pass through 110,000 microjets. It was an extremely complex project, and took almost two years to complete and perfect. Wanna see pics? I know just a tad about "piping".

 

Both check valves and drilled holes are a false sense of security and can and will fail, usually at the worst possible moment.

The only foolproof method is an air gap. Place your return(s) close enough to the sufrace so the yare exposed to atmosphere with a very small, easily calculated backfow and you never have to worry about a flood and can sleep soundly at night. Water cannot jump uphill so it is foolproof as long as you maintain sufficient freeboard or extra capacity in the sump to contain the 1/2" or so the dispaly will drop in a power outage.
In my case with a 100 gallon display it drops 3.8 gallons maximum which is easily contained in my 30G sump.

 

I agree 100%, but there are exceptions, and I've read many posts in the past where people were in a similar situation as I am. When I had a big tank, and big sump, all this was pretty much a non-issue. Now that I've downsized, it's become tricky, and this valve was my best bet. My present tank is only a 55, and I have one of those cheesy pine stands with virtually no room for a sump of any decent size. On top of that, I like tons of flow, so running my return close enough to the surface to prevent too much siphon with the power off results in so much surface movement that water splashes all over the place (including the floor lol). In order to achieve the flow and surface agitation I wanted, without splashing water everywhere, I had to have the return(s) under the surface far enough that (without the anti-siphon holes) it would overflow the sump. Now, if the anti-siphon holes were to get clogged somehow, I have added piece of mind with the valve. I'm definitely not trying to convince everyone that they need one of these, but merely that in my situation it was a good purchase, and may be for others too.

 

No matter how often or how well you clean and maintain a check valve, all it takes is a grain of sand or piece of food to defeat it. Remember, it does not have to be a catastrophic failure, even a trickle will overflow a sump in time and if you are not there to catch it you are done for.

There are no exceptions period. Drilled holes and check valves are no substitute for an air gap. Proper design is key.

 

I don't get why air gap is not possible on your tank??

 

A full inch of drop in a 55G tank is only 2.7 gallons. Not sure what you have for a sump but even in a 20G glass sump thats less than 2 vertical inches it displaces. If you are running your sump that full you are asking for trouble.

I only have a 30G sump and I have room for almost 10 gallons of backflow if it were needed. Any more water in the sump than that and the skimmer level is too high plus the baffles would all be under water and would not dissipate microbubbles.

 

I completely get, and understand everything you're saying, but I've tried positioning my return in every way imaginable to find a happy medium between flow/current, and sump capacity. I have a 1" outlet split into 3 nozzles returning to the upper right side of the tank. If they are too high they blow tons of bubbles into the water, or splash surface water everywhere, too low and they nearly blow the corals off the rocks. I've found the perfect level for them that provides the current I like, and tons of surface agitation, without making a mess. At that "perfect" level, (without anti-siphon holes) my sump will fill about 4", which brings the water right to the brim. The siphon break holes are the only thing I have preventing that, and I like the check valve as an added measure of safety. BTW, my total sump capacity is around 25 gal. I guess you'd have to "be there" totally understand, but the I have to run the sump fairly full for my skimmer to be at the proper depth.

We're getting ready to move, and I'm going back to a larger tank, but for now I think I've got this one running to it's peak efficiency.