Hi,

I was watching the videocast of the diy kalk doser and noticed that the float switch seemed to be wired directly inline with the pump. I have read that this wasn't safe because of switch failure. I just wanted to know if this the case and if you(Rob) or anyone has any input on this because I just got a couple of float switches in and I'm deliberating on whether to put a relay in the circuit.

Thanks
Chad

A normally closed soledoid on a float switch would give you the necessary redundancy to safeguard your tank. Grainger has them.

I wouldn't really worry about the relay for a auto top off. The relay is more specific to the volt surges when the pump kicks on.

If you use this float
i-float Float Switch (http://www.aquahub.com/store/ifloatfloatswitch.html)

With this pump
Tom Aquatics Aqua Lifter—Dosing Pump (Saltwater Aquarium Supplies > Overflow Box > Accessories ) (http://www.marinedepot.com/ps/ps_ViewItem~idProduct~OE1137.html)

You will be ok. Just wire the float into a normal white or brown extension cord and it will work like a dream. This is the setup i use on my top-off and it works great. Been using it this way for about 7 months now.

The failure is from the float not being able to handle the spike. The floats you get pre made from marine depot or someone else can handle the volt pike. The DIY floats can't handle it so you need the relay. But with the aqua lift pump is doesn't generate that much of a spike so it won't harm the switch. When the switch has a large spike it will heat the connections together inside almost welding them together and the float and won't let the pump turn off or on.

Thanks for the advice, I went out and got a relay today so hopefully all will work out great.

my switch runs to a relay, not hardline to the pump.
it actually has a outlet box that my pump plugs into, and the float switches the relay to power the pump on and off

Sweet, Mine is going to be set up the rest of the way this weekend I just need to go the harware store and get some tubing that will fit the outlet of my pump a little better. I tested it otherwise and it seems to work just need to do a road test.