Been there done that. If you rely on check valves to prevent flooding, you WILL have a flood. Maybe not a month or a year but it's not if you will have a flood, it's when. At least if you stay in this hobby. I've come home to find my house flooded and 500 gallons of water running out of my garage by way of the laundy room and down the driveway.
It's real easy to add an overflow. Keep your close look and closed loop. Have your sump feed itself from an overflow or at least or at the very least a point high enough that the siphon will break before your sump is overflowing. Same goes for the return. Have it high enough that your sump won't overflow before the siphon breaks.
Avoid check valves at all costs. Especially if you are in the middle of a new build, it's just doesn't make sense not to have to rely on them. Do it right the first time.
Yep agree, you have to build your system with no flood in mind, and yet have a good system for the livestock.
A redigned by plumbing and sump a numbers years back and eliminated all check valves and it was one of the best things I ever done. I haven't had a flood in years and I had more than a few before that.
Being in the computer business, I can tell you that while UPS's are great, the batteries seem to fail after about year and I don't use cheap UPS's either. Also, depending on the size of your pump, the amount of up time without AC power may be less than you think. I wouldn't want to rely on a UPS to keep my home from flooding if the power went out.
My $.02!
