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Re: Automatic water changer

Hi everyone,

There seems to be good response to Scott's inquiry re: Automatic Water 
Changers. This was originally sent to another member a few months ago. I 
decided to update it to my current tank situation and post it here as an FYI 
to anyone who might be interested

My water changing device is constructed of Rainbird and Toro Irrigation 
equipment, primarily. I will use a drilled tank as I describe the system. 
All of my own tanks are drilled, and they are all on this system. A drilled 
tank uses bulkhead fittings as I am sure you are aware. There must be a way 
for the water to go into and exit the tank without flooding the floor. I 
wanted this option even when I was not in the room. I use the 1 inch 
bulkhead fitting in my tank for the standpipe. I use 1" pvc pipe glued to a 
1" slip x 1" MPT fitting. The top of the standpipe in my All-Glass 125 g 
tank is level with the bottom of the vertical slits in the overflow. Use 
teflon tape on the male threads of your standpipe assembly. You may need to 
play with the standpipe length according to your filter flow rate, etc. An 
overflow box (like those on wet-dry filters) would work the same as a 
standpipe on your undrilled tanks. This will drive up your parts cost 
somewhat. The bottom part of the 1 inch bulkhead  on my tank is female 
threaded (just like the top). I use a 1" x 1/2" threaded reducer bushing and 
then use a 1/2" MPT x 3/8" barbed fitting. I then then use 1/2" OD x 3/8" ID 
polyethylene tubing to connect to the 3/8" barb. The poly-e tubing is what 
carries the waste water to the drain. I have a basement under my fish room 
so my drain line goes thru a hole I drilled in the sub floor behind the 
aquarium to a drainpipe in my basement. Just make sure the drainage point is 
lower than the tank, of course, as this is a gravity feed drain system. You 
could have it drain outside or into a utility sink, or whatever will work 
for you. You may wonder how the water in my aquarium gets to the filter as I 
use the bulkhead originally intended for this purpose for the standpipe. I 
use canister filtration, and use the intake for the canister and just hang 
it into the overflow area. It works great. I also keep a small sponge around 
the top of the standpipe to prevent any large debris or snails from entering 
the standpipe and clogging the drain.

The next section covers how to put water into the tank. My planted tanks get 
RO water and my other one gets tap water, so the configuration is different 
for the planted tanks. For the planted tanks I have my RO unit (50 gpd-Kent) 
dumping into a 45 gallon Rubbermaid trash can. There is a Little Giant 
submersible waterfall pump (La Bomba, about $65 from Home Depot) It has a 
26' head height, so pumping up 14 feet to my tank is no sweat. The pump goes 
to PVC Tee and to either of two Rainbird sprinkler valves ($14 from Lowes or 
Home Depot) connected to it. The valves are 1" FPT on both sides so the 
output side must be reduced to 1/2" and then use a 1/2" MPT x 3/8" barbed 
fitting (from Lowes). Then use 1/2" OD x 3/8" ID vinyl tubing to deliver 
water to the aquarium. I use polyethylene tubing on the drainage side 
because it is stiffer than vinyl so there is hardly any chance of it kinking 
and preventing the water from draining. The vinyl tubing comes up thru a 
hole in the subfloor behind the tank on the other side from where the 
standpipe is (it would not be very efficient to have the water entering and 
leaving the tank at the same location, would it?). I control this with a 
Toro sprinkler timer (Home Depot or Lowes about $35) The difference with my 
planted tanks is that you have to install a pump start relay for the 
submersible pump. This pump is not needed for my 90 gallon Discus tank as 
household water pressure flows the water to it. For the 90 gallon I built a 
PVC manifold that allows me to attach one of the above mentioned valves to 
the same water source (tap water). The valve turns the flow on or off when 
controlled by the timer. I also control the water that goes to my RO unit by 
means of a valve connected to the same PVC manifold. The pump start relay is 
available at any sprinkler system supply place. A pump start relay is 
basically a 12 volt switch that will turn on a household (120v) current when 
energized. In other words, the sprinkler timer will turn on the pump start 
relay, and the relay will turn on the pump. These are used by people who 
irrigation out of ponds, rivers, etc., where they do not use household water 
presure. Mine cost $22. Sprinkler timers are low voltage systems, so they 
are not very dangerous. My sprinkler timer is mounted on a wall in a closet 
in the fish room. Wire it with sprinkler cable (same area as valves, 
sprinkler timers, etc in Home Depot or Lowes). The timer allows multiple 
on/off times, and run times from 1 minute to 4 hours. I use adjustable flow 
Rainbird valves. This allows a fairly slow flow rate of water into the tank. 
I do small amounts of water several times a day. That way you do not have a 
severe temp fluctuation in the tank. I have my valves adjusted on all three 
tanks to flow approx 1/2 gallon a minute. The volume is adjusted by the 
amount of time you keep the valves open (using the timer). My 125 gallon 
planted tank gets new water 4x daily for a total of 5 gallons a day. My 90 
gallon discus tank (bare bottom) gets new water 8x daily for a total of 24 
gallons a day. My 65 gallon planted tank gets new water 5x daily for a total 
of 2.5 gallons a day. The water to the 90 gallon is run thru an in-line Omni 
Whole House Water Filter (behind the valve). These are about $22 each and 
have a life of 15,000 gallons (Lowes or Home Depot) or three months. The 
filter catridges are the 5 micron GAC type and cost about $5 each (cheap). 
This removes chlorine going to the 90 gallon.

The system has been up and running for over a year now without any problems. 
Additionally, the RO unit and the reservoir in the basement are each inside 
containers plumbed with bulkhead fittings serving as overflow/leak 
protection. These empty into the same drainage point the tank water goes. 
The drainage point is the stub for a basement toilet. I modified the PVC cap 
to accept the drain line from the tanks/overflow bulkheads.

The wiring looked a bit intimidating at first, but it was not a big deal.  
It was a great project for a gadget freak like myself. This is a broad 
overview of my system. If anyone has questions or needs clarification please 
email me off list.


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