How do I keep this catch basin level?

I am working on a pool that seems to have a poor design. The pool has a small negitive edge that trickles down some rocks. This trickle process is part of my problem the basin will run dry after a few hours. Thought about installing a float switch to the pump to kick off when it got so low. Any help getting my head wrapped around this would be great. 864 844 1157 if anybody wanted to call.Jared mize

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  • Check valves fail over time. It would be good to use valves that are both veiwable and repairable.

    A second line of defense is to install a valve that will open to the atmosphere when the pump is turned off. Install it on the return line to the upper basin and well above the water level. This is a trick of Tom S., the Pentair automation king. When the pump shuts off, the valve opens to the atmosphere and allows air into the return line, killing any siphon effect.

    Can we put a skimmer in the basin if the front hole is plumbed to a large balance line and the back hole goes to the pump?

    Has anyone used a Smartmiser (radio signal) to control a 24 volt

    valve in the mechanical room?

    Rob Lane

  • Without check valves the water is siphoned back to basin, the check valves will also help in start up. 1 2" jandy check valve is what I would do first. You said when you shut off the system the basin overflows, this is pool water flowing backwards though the system. I have built 100's of pools like this, keep it simple. Whatever water you pump out of the basin is equal to what you pump into the pool (over the weir), your pool level should be right at the edge of the spill over when the system is off. Never put a skimmer in the basin.

  • There are no check valves the pumps sit above the pool. I think Bruce is right about the pump. This pool has a 3/4HP pump that I can install on the basin. I am going to plumb it so the pump supplys  the returns in the basin. There is a line that will supply two returns in the pool . My thoughts are, if most of the water stays in the basin and the water that goes to the pool is filled slow then it should not run dry.

  • To follow up on Glen's question about the check valves. . . 

    When the pump shuts off and water stops flowing over the negative edge, does the water level in the pool stay right at the level of the negative edge, or does it drain down below the level of the edge. If it does drain down, the system may have a bad check valve or it may need to have one installed in the system that pumps water from the basin back to the pool.

    On the other hand, if the water stays right at the level of the negative edge, then Bruce's point about the pump size might be right on target.

  • Are there check valves?

  • The quick thought is that the 2 HP pump may be too big for the trough, and is emptying it faster than the make up water can return.  Typically, a Sheer Descent uses 1 gpm per inch to flow properly, so if the SD is a two footer, you would only need 24 gpm for that.  The 2 HP pump is pulling well over 100 gpm, so it could be "outrunning" the water available.

    Just a thought at this point!  I'll look for picture later (and maybe you could put up how long the edge is also-I'm thinking it is not just an 18" edge).

    Just another quick question:  Have you checked how level the edge is?

  • The basin has a 2HP pump. The basin main drains feed the sheer decent and two returns in the pool and trickle down is gravity feed. The edge about 18 inches wide and sits about the middle of the tile I can attach pictures tomorrow.The pool has one skimmer and main drain that feed in-floor system.

  • Does the trough (edge) have a dedicated pump Jared?  I'm also wondering how deep and wide the trough is. 

  • Thanks for your reply. Running this pool off timer is our goal. When we shut the system down the basin would over flow. I have plugged the overflows to allow for the extra water. I may have to raise the neg. edge. So at this point the trickle has stopped and the basin is full but not overflowing. My problem is starting the system up. Half of the water in the basin  is needed to start the trickle down. So now the basin is half full with the system ruuning but wanting to run dry. The basin has an auto fill. My issue is when the system shuts down all water added from the autofill now goes out the over flow. My thinking was the basin needed to run at half full or whatever the amount of water it takes to start the trickle effect. What are the principles in the design of a sysetm like this to keep it from running dry or over flowing?

  • Most catch basins have an auto fill valve that adds fresh water to ensure a minimum required level whenever the level in the basin drops too much. If a lot of people are in the pool, the basin will catch the overflow of the pool and fill beyond the minimum level. The pump that draws from the basin pumps back into the pool to keep the pool at a constant water level regardless of how many people are swimming. If the basin is getting too low, that tells me that there is not enough total water in the pool and basin combined. Unless the basin is too small and overflows when the bather load is high, there shouldn't be a problem. An auto fill in the basin should be able to add water fast enough to keep up with splash out and evaporation.  

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