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Zapins 09-23-2009 06:23 PM

Automatic water change system design DIY
Well now, for once one of the APC site adds actually had something relevant that I could relate to for once... Sadly for them I saw their add too late for it to matter... bawhahahahaha

My water change setup is relatively easy to make. The basic design involves three parts: an overflow, a fresh water source, and safety features to prevent overflowing. This water change system is continuous (meaning it runs 24 hours a day at a very slow rate). I have well water with no chlorine, or added softening salts. My tanks are conveniently placed in the basement where this water change system is set up.

Overflow System:
Essentially I built an overflow system out of 1.5" PVC pipe that hangs on the back of the tank, and then added a long corrugated garden drainage tube onto the PVC overflow and drilled through my sheet rock wall.

A little note on overflow systems: Overflow systems, for those that don't know, are just tubes with a U turn in them where the water permanently stays inside the U bend. What ends up happening is that if water on one side of the U bend is raised then water spills out the other end of the U bend. When the water level in the tank gets too high the excess spills over into the drainage pipe.

Overflow concept:

First overflow I built:

Second overflow I built:

From there the drain pipe runs into a 60g plastic tub from home depot that sits in the boiler room behind my tanks (on the other side of a sheet rock wall).

Drain pipe seen from behind the sheet rock wall:

Drain pipe and 60g sump bucket:

Once the water is in the bucket it must be pumped out on a regular basis. At first I bought a 1/3 hp sump pump off ebay, but as does occasionally happen it arrived broken, incapable of pumping water. The float valve that controlled the sump did work though and so instead of connecting the sump pump to the sump float switch I connected an aquarium pump to the float valve (very easy to do, I just plugged the pump into the float valve's power cord). Now what happens is: when the water level rises and triggers the sump float switch the aquarium pump turns on and pumps the water into a PVC pipe (1" diameter) that I have running outside. I had to drill through the concrete basement wall which entailed me renting a large rotary drill from home depot for 42$. The PVC waste water pipe runs into a gutter drainage system we have outside (preexisting system).

Inside the sump:

Waste water PVC pipe through concrete basement wall:

Fresh water source:
The second part of my water change system involves getting fresh water into the tank. I chose to use ice-kit maker saddle valve taps (cheaply bought from home depot) because they are very easy to install and can be adjusted to allow a few drops an hour to several dozen gallons per hour through them. I installed two saddle valve taps per fish tank on the water change system. One valve was put into the cold water pipe, the other valve in the hot water pipe. I joined the tubes with a 3-way easy connect joiner and placed another valve in the hot water line before the 3-way connect joiner so that I can precisely control the hot water going into my tank.

Saddle valves connected to house water mains:

3 way connector and hot water valve:

The water tube is then fed through the wall and connected to a small mount which I built on the side of my tank out of PVC pipe. The mount holds a plastic float valve. The water tube is connected to the float valve. I came up with two designs, I prefer the second one :)

Second mount design:

Second mount underside:

Second mount in tank:

Safety features:
The first safety feature I installed was to add a float valve to the incoming water tube. The float sits inside the fish tank and is attached with a PVC pipe mount (see above). The purpose of this float valve is just in case the overflow gets clogged for whatever reason (leaves, dead fish, etc...) the incoming water will start to rise and then push the float valve up, stopping the incoming water before the tank overflows.

The second safety feature I added was a solenoid in the incoming water tube. A solenoid for those that don't know is just a magnetically controlled valve that opens and closes depending on whether electricity is flowing through it or not. My solenoid is designed so that it is usually closed when unpowered, when power is supplied to it, it opens and allows water to pass through. The reason this solenoid is necessary is because if the sump overfills for whatever reason (pump dies, sump pump float switch gets stuck and doesn't trigger the aquarium pump, etc...) then the solenoid should be triggered to shut incoming water into the fish tank, preventing the sump from overflowing. The way the solenoid pump knows how to do this is because there are two float switches (two for redundancy and more safety) placed at the top of the sump bucket. If either of these two float switches are triggered by rising water then they send a signal to a relay (an electronic device necessary for this kind of use) that cuts the power supplied to the solenoid, thereby closing it and stopping anymore water from flowing into the fish tank and consequently preventing anymore water from entering the overflow and sump.

Solenoid in fresh water tube:

Float switches in sump pump:

The power strip and relay that controls it.

If you look carefully in the above picture you will see that there are two power strips. One of the power strips (left most one) is wired into the relay. Basically the relay controls the power strip itself and the float switches in the sump bucket control the relay. So what ends up happening when water rises too high is the float switches are triggered, they send a message to the relay box which cuts the power leading to the power strip and since the solenoid is plugged into the power strip, the solenoid loses power too and closes. I chose to wire a power strip to the relay because I will be adding more tanks to my water change system and therefore I need more solenoids to individually control the incoming fresh water to each tank. The beauty of this arrangement is that if the float switch is triggered in the sump the relay shuts off power to all solenoids and all incoming freshwater to all tanks is shut off. This way no tank will be able to add more water to the sump. In addition, each tank functions individually from the other due to the float valves mounted on each tank. If one tank's overflow gets clogged then only that tank will shut off the incoming freshwater. Each tank functions separately, but is united.

Relay assembly instructions (this is how I wired my relay and power socket)

This is essentially how I have my relay, power strip and float switches set up, just instead of inside a tank it is all inside my sump:

Relay setup:

Approximate Costs for adding 1 tank to a water change system
Overflow system
10 feet of PVC tubing at 1.5" diameter for overflow and tank mount - $3 -- from home depot
3 U bend PVC joiners - $8 -- from home depot
PVC cement - $3 -- from home depot
1 90 degree PVC bend - $0.70 -- from home depot
1 PVC 1.5" joiner with female screw (used for attaching a bard for the waste water pipe) $1.50
1 black corrugated 20 foot waste water drain pipe - $9 -- from home depot
1 pack of 12 zipties for securing waste pipe - $1.50 -- from home depot
1 garden 60 gallon sump bucket - $39 -- from home depot
1 aquarium pump - $30 -- from ebay
1 sump float switch - ??? -- from ebay
1 basement hole in the wall - $42 -- rented drill from home depot

Total: $137.70 + ??? (sump float switch) (includes tax and shipping)

Fresh water
20 feet of polyethyline tubing (1/4") -- $3 from home depot
2 saddle valves - $14 -- from home depot
1 three way quick connect tube joiner - $3 -- from home depot
1 valve for hot water - $7 -- from home depot

Total: $27 (includes tax)

Safety features
1 Relay kit with float switches - $46 -- from
1 float valve for in tank - $14 -- from ebay
1 reel of electrical wire (for solenoid) for 90 feet - $8 -- from radioshack
1 power strip - $8 -- from home depot
1 solenoid valve - $21 -- from ebay
2 plastic fittings for the solenoid valve - $3 -- from home depot
Total: $ 100 (includes tax)

Grand total: $264.70

Not a bad price in my opinion for never having to do another water change ever considering lights can cost about this much for larger tanks, and CO2 systems come close.

I have plans of adding flood detectors that sound an alarm so I know if a tank is overflowing, but I'll leave that for a later post.

LuisVillalobos 09-23-2009 06:58 PM

Re: Automatic water change system design DIY
Wow that looks amazing!
kinda complicated but it would be really usefull!

niko 09-23-2009 08:39 PM

Re: Automatic water change system design DIY

I'm blown away.

I'm considering experimenting with a 180 gal. tank and constant drip system. The tank is full of BBA and I know it's because of organics. Conventional water changes every few days don't do anything.

I also saw a local monster fish keeper guy that has many huge fish in a 180 gal. tank. Looked totally crowded. Tank looked artifically clean. Like he bought the tank today and just filled it up with water 1 hour ago. But it's been running for 3 years and the silicone looks brand new on the inside. The huge fish are unbelievably healthy. Not a single small piece of anybody's fin was even split! We eat fish smaller than the monsters he had! They also eat 2-3 lbs of food a day! Continuous injection of Prime in the incoming water.

So! Have you seen any considerable benefits from the continuous water change compared to the old bucket & hose grampa approach?


Zapins 09-23-2009 08:54 PM

Re: Automatic water change system design DIY
Thanks for the kind words.

Niko - I have seen some pretty huge benefits in my 55g tank so far. The first is that the water is very clear, as if I had been running a diatom filter or two or three constantly. The fish seem more lively since the incoming water has a lot more dissolved O2 in it. Circulation seems to have improved quite a lot since the incoming water moves water away from a stagnant corner and the plants have been growing wonderfully. I've got some rotala rotundifolia that has turned pink nearly all the way to the bottom - its never done that before for me and I'm only using 2x55w of PC light on the tank!

I am very happy with the WC system so far. It has only been running for about a week now and already the results are clear. Its true what they say - the more WC you do the better the tank!

I think this system is highly modifiable. It would be easy to set up an automatic dosing system with this kind of system or add a dechlorinating device to one of the tubes, or heck even add another sump and a few timers and get the tank to drain first and then fill up in one go (not constant water flow). A reverse osmosis machine could be added to one of the fresh water tubes and mixed with incoming water, all that is needed is just a couple of 3 way junctions and a few inline valves which are cheap as dirt.

I have been thinking about a cheap method for fertilizing a constant auto WC tank setup like I have. All that is needed would be another solenoid valve connected to a digital timer and a large container with fertilizers in it that is placed above the tank. The solenoid would allow fertilizers from the container to gravity feed down into the tank at regular intervals throughout the day and night to ensure very, very stable and consistent dosing (since the constant water changes would be removing excess). I think such an auto-fertilizing system wouldn't cost more then about 25-30 dollars total, since the timers are about 5$ and the solenoids are roughly 21$, tubing and a small valve are cheap/negligable. I'm going to give it a try and I'll post the results in another DIY thread. I've already got 2 solenoids coming in the mail. A peristaltic pump wouldn't be necessary at all for this, which lowers price considerably.

I plan to connect a 180g tank (with discus) to the auto WC system in addition to the 90g and 55g currently running on it. Once the auto water change system is complete adding additional tanks is EXTREMELY cheap. Basically the only things needed are another overflow - which is mainly made from cheap PVC pipe ($10 max), a length of corrugated drainage tube which is also cheap (20 feet for 9 bucks), and a 14$ float valve off ebay.

zap's Mom 09-24-2009 12:59 AM

Re: Automatic water change system design DIY
Great job zapins, and you didn't even flood the house! :clap2:

Seriously, apart from my fears of the worst happening, I am relieved, and kinda proud to see how you did such a great job.

Also, I am happy that neither you (nor I) will have to do another water change!

Now, about those other DIY jobs I have in mind for you....

zap's Mom 09-24-2009 01:01 AM

Re: Automatic water change system design DIY
Hey! It's weird that you are senior here, and I am junior!

But don't forget who's boss, lol.... despite what your dad says, it's ME

armedbiggiet 09-24-2009 02:08 AM

Re: Automatic water change system design DIY
wow, this one actually make sense. I lik ethe second one alot, What you did it is the same idea for toilet!! but I can not figure out how the water going to flow with the air inside. I know the second part of the curve you got a hole for it but how about the first one that is part inside of the tank?

armedbiggiet 09-24-2009 02:40 AM

Re: Automatic water change system design DIY
does the first run the water run by itself of you have to fill the first pipe with water?

Zapins 09-24-2009 04:19 PM

Re: Automatic water change system design DIY
Initially the overflow needs to be filled with water. See the 1st diagram for an idea. I just stick a plastic tube in the overflow and suck out the air with an aqualifter pump. Once it is set, it doesn't need to be tinkered with again unless the overflow dries out or bubbles build up in it and break the continuous water section. It is totally self functioning after initial set up.

TAB 09-24-2009 04:28 PM

Re: Automatic water change system design DIY
I hate to sound like a A hole, but that system is a flood waiting to happen.

saddle valves and plastic lines ( more so when near heat ) are also floods waiting to happen.

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