SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

a floating intake is a great idea for several reasons, including the already-mentioned area of clearer water near the surface of many ponds

better off to not bother with a foot valve in the pond, if you can manage with a check valve at the pump inlet

if you use a long filter screen attached to a wood plank float, all that's really visible is the plank

Depending on your location, you might very well want to have the water able to drain back through the suction line, as it can help preparing for winter. As long as the pipe and check valve and connections are good, the water won't be draining back into the pond, as that would create a vacuum. Much better to rely on a check valve at the pump inlet than a foot valve in the pond, if it comes down to them requiring service, and the repairman not being eager for a swim.

I service a number of systems that have both check valves before the pump and foot valves. They all have long runs before the pumps and sit several feet above the intake. Really not practical to not have a foot valve. The check valves make them difficult to prime and difficult to drain for winter. In one case, whoever installed it installed a check valve on a vertical stretch of PVC and buried it in 6" of sand. With no practical way to get the water out and really no way to tell that the intake line was still full of water, the thing froze and was replaced sans check valve the following spring. Works much better.

Quoted from "SunCoLawns"

I service a number of systems that have both check valves before the pump and foot valves. They all have long runs before the pumps and sit several feet above the intake. Really not practical to not have a foot valve. The check valves make them difficult to prime and difficult to drain for winter. In one case, whoever installed it installed a check valve on a vertical stretch of PVC and buried it in 6" of sand. With no practical way to get the water out and really no way to tell that the intake line was still full of water, the thing froze and was replaced sans check valve the following spring. Works much better.

I'd love to hear an explanation of how a foot valve presents no problem when draining a suction line.

Any check valve, be it foot valve or inlet-mounted check valve, will interrupt drainage through the suction line. That's what they're for. In the event of a higher suction lift, you do want a foot valve, or a check valve lower in the line, close to the water level, so that the height of water has a check valve to sit on, which in turn takes a load off the pump.

Since I use jet pumps almost exclusively (good self-limiting output pressure for sprinklers) I can fit them with an 1-1/4 inch brass check valve at the inlet, and forget abut any foot valves. These are all installs with a lift of about five feet, so there's no lifting strain on the pump. The smaller check valve sizes can also be had in a version with taps on either side of the check, for use as "control center" valves for indoor well water supplies, and it is that tap that makes suction line drainage an easy thing to manage, so long as there's no foot valve preventing drainage. My priority is to not have to venture into a very mucky pond in order to deal with suction line issues.

For larger size suction connections on a pump, the brass check valve may cost way more than a foot valve. And of course, if you are in a warmer climate, you may not have any freezing worries with the suction line, so no foot valve worries.

Unscrew the foot valve - problem solved. You may be using them in different applications than I encounter. Most of mine are in recreational lakes and are tied to a dock. One of them has a union coupling on the beach and it is removed and the entire line is taken out of the lake.

Definitely a different application. I get small shallow ponds and lakes that are struggling against their eventual demise by becoming filled with leaves that won't break down quickly enough. We employ oversized screen assemblies attached to a plank, floating some distance from the edge of the body of water, so that clear water can be brought in from close to the surface, away from the leaf litter 'sludge' that is barely a foot from the surface.