Peter asked people with "water" experience to own up.
Some may say it is foolhardy for me to offer advice after so recently
admitting to pumping thousands of gallons of my rainwater reservoir
onto my floor but her goes anyway.
If you are into electronics, Isuppose build a system from scratch is a
reasonable approach. On the other hand, commercial stuff is readily
available. After years of trying out all sorts, I now use a small
aquarium pump which cost about 20-30 pounds (UK). I pump this into
a standard small plastic cistern (the sort that holds water in the loft).
The cistern acts as a constant level device so, when full, the water in
the cistern is at the level I want in the grow areas. To maintain the level,
I use a very small float switch, cost about 10-15 pounds. This is a small,
tidy and sealed plastic switch that fixes easily into a hole drilled in the
cistern.
For safety, you would ideally duplicate pump and float switch into the same
cistern.
>From the cistern, use pipe to connect water to constant level trays.
>Easist
way to get the best treays is to buy black sheet plastic and build them
yourself to your preferred size. Use silicone ruibber glue (from
aquarium shop of any DIY outlet) to glue to sheet wherever you join it
(hint: don't be stingy - run the glue along all the inner bends and
joins. Water will find any weakness no matter how small so seal
everything first time!)
In the UK, there are two main suppliers for this sort of kit. "Two Wests and
Elliot" are best known. I use "Simply Cointrol" in Wichester. Both do mail
order. If enquiring, always explain your need and ask them to recommend what
they can supply to meet the need. They often have items not listed in the
catalogue.
Both shops are probably listed in garden source books and magazines.
egards
Paul