check valves for ballast

Just installed an auto ballast, but water back siphons, so anybody know where to get check valves to stop this? I need three.

you can get them at home depot. Ask for low -back pressure vaulves and ake sure you install them cap up and you should be good to go.

http://www.wakeworld.com/Articles/2001/BallastSystem2.asp

On the fill lines or the empty lines? Or are you using a 2-way pump so the fill and empty lines are the same line? If it is only on the fill lines, then what Chris said is true. Just get some cheap $3 check valves at Home Depot and pop them in the middle of the line. If you are also siphoning out through the drain lines (like I was on my Malibu) you will need to buy some electronically-actuated valves that open when the drain pump is turned on. I got some from STC valve Co. in California for about $60 each.

I got mine here:
http://www.plumbingsupply.com/pvccheck.html

get Swing Check, not Spring Check valves. The swing valves have a simple flapper that lets the water flow in one direction. Spring Checks are pressure activated and would not be good for most ballast pump systems.