Re: Water changes

["Bill Wichers" <billw at waveform_net>]

>to be pumped out to plants as well.  Hate to waste it down the drain and
>into the septic.

The runoff from your septic system's drain field will probably eventually 
get to your garden, so it's not wasted :-) 

[snip]
>Your idea is wonderful but I have a couple of questions.  I am looking for
>something I can automate and not have to mess with.  I have a sprinkler
>timer to turn things on/off.  If I put the powerhead down to the level I
>want the tank drained to and put it on the timer, the following should
>happen? Timer powers on powerhead, it starts sucking for a couple of minutes
>until the timer kicks it off (before the water is down anywhere near the
>powerhead) water will continue to siphon until the pump is out of the water
>and the siphon should break then.  Several minutes later, another program on
>the controller will kick on the water input, which is a separate line
>obviously, to refill the tank until a float switch trips. (unless Bill has a
>better idea!)  The drain line will have broken siphon prior to this point
[snip] 

I'd go to home depot and get a automatic sprinkler valve (which is really 
just an inexpensive solenoid valve). They usually run on 24v, and if you're 
using a sprinkler controller to run things you probably already have 24v 
outputs available since the unit is going to be designed to run these 
valves. Program the controller so that it turns on the powerhead and the 
valve at the same time, and off at the same time. The valve will for sure 
stop the siphon when it closes, so you can have absolute on/off control of 
the water changer exactly when you have it programed to turn on/off. My 
expierience with my system is that the powerhead sucks a lot of air when the 
water level gets near the intake, and this might be a problem for the 
powerhead over time if it happens a lot. The solenoid valves are fairly 
cheap at some $10-20 at home depot. You'll need some thread adapters to get 
them to standard sizes, or you could just use vinyl tubing for the hose and 
get the correct fittings for the hose to screw into the valve. 

If you put the valve at the far end of the hose, you could probably get the 
system to be a controlled *siphon* instead of needing the pump. Probably not 
as reliable, but maybe a neat expieriment. 

>Daphne who is so excited about Bill's post!

Glad you found my post so inspiring ;-) 

BTW, you could use a second solenoid valve running directly on house water 
pressure to allow a programmed tank-fill cycle. Those sprinkler valves are 
made to operate that way after all. 

    -Bill 


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Waveform Technology
UNIX Systems Administrator