# Easy DIY automatic water change system for less then $50



## Zapins

Yes! I just finished making my very own automatic water change system for 50 bucks. I have been meaning to do something like this for years and years but I always overcomplicated the design thinking I'd need multiple safety features and float valves etc... Nope! Here is a very simple design for a continuous water change system that really only requires a few parts:

This is what the final product looks like. I decided to mount it on the wall in a spot that I could access it easily, but it could very easily just be mounted behind the tank so that nothing except the water intake tube sticks over the edge of the tank. You can also make the system in black PVC so that it is less visible.










This is what will be visible inside the tank










I went about making this system using the idea of an overflow. Basically an overflow is a partial siphon that never fully drains out the tube of water. It responds to an increase in pressure (from the water on top of it in the tank) by pushing some water out of the waste water pipe.

Here is a diagram of what I am talking about:









*In a nutshell the important concepts of an overflow are:*
The water intake pipe needs to be at the same level as the waste water pipe (seen on the right) to work properly. A hole is also needed above the waste water pipe to equalize the pressure otherwise a constant siphon will be formed when water is added to the system and it will drain all the water out of the tube. To make an overflow, water must remain in the tube at all times and any bubbles trapped within the solid blue section must be removed for proper function.

But for those less familiar with the physics involved in why this works:
Looking at the diagram, water needs to be in the solid blue part of the tube, this means that there should be solid water in the tube from the intake (on the left) to the waste water tube (on the right) with no air bubbles. When this situation is achieved what happens is if pressure is applied to the water intake side the water in the tube has no place to be pushed out of the way except through the tube. The compressed water is forced through the tube and out the waste water side on the right. If the object applying pressure is a slightly overfilled tank then the water itself will be sucked through the tube and out into the waste water end.

Very important to all this is the fact that on the waste water side a hole must be cut on the upper part of the tube. This hole allows the air pressure to equalize which lets the water sit in the bent tube shape permanently. If the hole was not there then a siphon would be created and siphons tend to suck all the water out of a tube making it useless for multiple uses!

Here are a few pictures of what I started out with. These are just generic plumbing PVC tubes, bends and parts that you can find at any hardware store for a few measly dollars. I used PVC pipe joiner to glue them together.




























Now that the drainage part is constructed the only other thing to do is tap into your house water main! Now, if you are like me, you will probably be nervously shaking your head right now scrambling to click the back button to get out of here. But! Have no fear! A company called Watts makes an ice-maker installation kit that is designed to clamp onto your main copper water pipe and make a small hole in it, allowing adjustable water flow. All you need to do is buy the kit, screw it onto your a _cold_ water pipe somewhere in the house (this can be a sink, bath, boiler copper water pipe of ~1 inch diameter) and turn the knob for fresh clean water!

This is what my pipe looked like after I screwed it in:









Then I snaked the copper tube through ducts in the basement and made a small hole through the wall right into my fish tank!










This is what the tube looks like coming into the tank from the wall:










I chose to put the the fresh water from the copper tube on one side of my tank and the overflow on the opposite side of the tank. This will ensure that the freshwater you are adding (cold water) will sink to the bottom of your tank and by the time it warms up and rises to the opposite side where the overflow is located (near the top) it will be old water.

*Word of caution** if you have chlorinated water I would set the flow rate very low, a few drips per second so that the chlorine has a chance to degauss and not kill your fish. If you have chloramine in your water... then I suppose this won't work for you at all. Also, if you have a water softening system on your house that adds salts to the water to make it softer you should add the ice maker tube to the copper pipe *_*before*_* it enters the salt softening machine, this will ensure that only fresh water enters your tank. Well water users will be fine at whatever flow rate they desire since no chemicals are added to their water pipes*

And that is it! All you need to do now is turn the ice maker tube on ad the desired flow rate and fresh clean water will flow into your tank and be constantly drained down the overflow. The large 1.25 inch diameter PVC tubing overflow will not get clogged since it is so wide, and since the water level sits at the lip of the water intake pipe. Fish, and leaves won't have a chance to cover the entire opening. Even if they did, the steady trickle of water coming in (assuming you choose a slow flow rate) won't overflow the tank quickly, so the most you are looking at is a few gallons of mess per day, which really isn't that bad. I plan to design an alarm to notify me if the tank is overfilling, I'll post the designs for that soon. Enjoy!


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## rbarn

Copper + Aquarium = Bad.

Good idea though.
Another reason to run a sump, you get to hide all that in the sump.


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## Zapins

Well not really, all the water tubes in your house are made of copper and we use them for fish tank water. Also, metallic copper doesn't dissolve readily into water especially if it is cold water that is not exposed to the air. Alternatively if you are worried about using the copper ice maker kit they sell a plastic alternative that you can use in the exact same way.

I chose not to go with a sump, because that adds another layer of complexity to the system, and with more complexity comes more of a chance that something will go wrong in the system and cause an overflow problem.


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## rbarn

Zapins said:


> I chose not to go with a sump, because that adds another layer of complexity to the system, and with more complexity comes more of a chance that something will go wrong in the system and cause an overflow problem.


Zero overflow chance if done right.
Sumps look more complicated than they are.

I'm planning to do an overflow just like you have for your tank
into my next sump.


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## bpimm

Looks good.

Same basic system I've been using for 20 years.

A couple things I would consider would be a piece of sponge in the overflow to keep junk out, I thought it wouldn't be able to plug also.......

In the top of your siphon tube where it goes over the top of the glass will slowly fill with air from out gassing, very slowly, maybe 6 mos. to a year it will break siphon because there isn't enough flow to keep the air out. My fix was to install a small barb fitting in the top and run it to the suction side of a pump, either a filter pump or the aeration input on a power head will work, this will keep a small amount of water flow in the siphon tube and keep the air out. It will also start the siphon for you when you first set it up.

You could also get rid of the upturned skimmer portion and have the intake under water with a sponge plug, this cuts down on the amount of stuff that can plug the overflow. The level of the 180 with the air hole will set the water level in the tank.

I have used the skimming and under water styles both and over time I have changed away from the skimming variety because they almost always plugged eventually.

Just a couple things to consider, but after having a water change system I'll never go back to hoses and buckets.


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## CraigThor

I'll try and find the link but dripping water in this was doesn't equal a full water change. I previously had a drip system setup for my old 150g Peacock Bass tank. I was dripping 4 gph 24/7 into this tank and it was equal to a 20% water change weekly as some new water will make it out with the old water.

Craig


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## Zapins

Hmm interesting. I was thinking of adding a barb or a small valve at the piece that goes over the tank's side to make filling the tube easier. Thanks for the warning about degassing. I suppose if I have CO2 up really high I might have to be more careful with that.

Can you make a diagram to show what you mean by this? I don't understand how it will work.



> You could also get rid of the upturned skimmer portion and have the intake under water with a sponge plug, this cuts down on the amount of stuff that can plug the overflow. The level of the 180 with the air hole will set the water level in the tank.


Also, in your experience how often does the overflow design (like in the picture above) get clogged? Or does it ever get clogged enough to stop flow?


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## CraigThor

http://www.monsterfishkeepers.com/forums/showthread.php?t=123422

http://www.monsterfishkeepers.com/forums/showthread.php?t=71419&page=2

http://www.monsterfishkeepers.com/forums/showthread.php?t=19920

and from this post here is the fuguring the drip numbers:

http://cichlidforum.com/phpBB/viewtopic.php?t=145173&highlight=&sid=0efd01b4a575c306811d502caae8e977

Great water change set-up. I have a continuos drip system also. The benefits are really second to none.

A math professor and I have written a program that can figure out some stats for water changes. I'm currently working on a web version of this program.

Some stats based on a 150g tank- 
2gph = 126.1 ml's per minute 
You'll be using 336 gallons of water per week.

At 2 gph rate of change, the water qualitiy will be equivalent to doing a -

70% weekly water change, which uses 104 gallons of water. 
or 
53% water change 2x per week, which uses 160g of water per week. 
or 
24% daily water change, which uses 255 gallons per week. 
(The fish will recieve no osmotic stress from a drip system water change. 
whereas A 70% is potentially very damaging to fish)

At 2gph the nitrate's will be-

If 1 ppm of nitrates are accumilated per day = The Nitrates will plateau at 3.15 ppm in the tank 
If 2 ppm = 6.31 ppm Plateau 
If 3 ppm = 9.5 ppm Plateau 
If 4 ppm = 12.61 Plateau 
If 5 ppm = 15.76 Plateau

Craig


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## Scouter

Great idea! It looks like you have a canister filter. Maybe you could connect the system to the inflow of that rather than the overflow pvc tube in the tank? I think that would work, since water is still drawn in from the filter anyways. what do u think? 

Scouter


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## bpimm

Zapins said:


> Hmm interesting. I was thinking of adding a barb or a small valve at the piece that goes over the tank's side to make filling the tube easier. Thanks for the warning about degassing. I suppose if I have CO2 up really high I might have to be more careful with that.


Just the ease of starting the siphon makes it worthwhile for me.



Zapins said:


> Can you make a diagram to show what you mean by this? I don't understand how it will work.












Once the siphon is started the output where it flows into the drain line will set the level. you need that point at the water level like you have it drawn, the intake can then be underwater and less prone to plugging, Mine were always smaller pipe so plugging was more of an issue, Nerite snails are a good plug for 1/2" PVC.



Zapins said:


> Also, in your experience how often does the overflow design (like in the picture above) get clogged? Or does it ever get clogged enough to stop flow?


Mine would get crud in them and stop flowing enough to overflow the tank, that's why I got rid of the skimmer type, yours being 1 1/2" may never plug

Most of mine are drilled through the tank wall and I just put a piece of sponge in the bulkhead fitting and that needs to be cleaned on occasion, I had one plug after about 2 years so when ever I do a major cleaning I wash out the sponge.

If I had to do manual wc's I wouldn't have tanks, In the summer when I go racing the tanks are lucky to get fed a few times a week, I haven't done any maintenance on my tanks for about 3 Months now, I'm sure they would be a real mess without wc's.


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## Zapins

Hey now! That is a good idea! I suppose I would have to fix the loop of the pipe outside the tank extremely well to the wall to make sure the water level doesn't change there and cause a problem, but that sounds good. I think I might try that one out on my 90g, or the 180g later on seeing as though I've already epoxied the tube together.

I am worried that it might overflow though. I think I might just add another overflow onto the 55g like the one you posted for insurance. If one gets clogged the other underwater probably won't be.

I think I'll also add an alarm. I think I can easily make one with parts from radio shack that will let me know if the tank is overflowing.

Something like this


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## Revernance

Zapins said:


> Hey now! That is a good idea! I suppose I would have to fix the loop of the pipe outside the tank extremely well to the wall to make sure the water level doesn't change there and cause a problem, but that sounds good. I think I might try that one out on my 90g, or the 180g later on seeing as though I've already epoxied the tube together.
> 
> I am worried that it might overflow though. I think I might just add another overflow onto the 55g like the one you posted for insurance. If one gets clogged the other underwater probably won't be.
> 
> I think I'll also add an alarm. I think I can easily make one with parts from radio shack that will let me know if the tank is overflowing.
> 
> Something like this


Looks good!  I'm interested to see it work!


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## Zapins

Ugh, unfortunately I won''t be here for the next 5 weeks. I might be able to log onto APC on and off, but I won't be making the alarm itself until I get back from vacation.


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## hydrophyte

Nice work. Thanks for this detailed post! I saw something similar in a fishroom that I visited recently. I am surprised that nobody manufactures anything like this for sale.

Where are you going on vacation--someplace tropical, with lots of biological diversity?


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## macclellan

Nice writeup!

Any reason that the tube needs to be so big? I could do this with extra canister filter parts. Much less visually intrusive.


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## CraigThor

macclellan said:


> Nice writeup!
> 
> Any reason that the tube needs to be so big? I could do this with extra canister filter parts. Much less visually intrusive.


Smaller tubes = less flow, faster clogging, more likely to fail in the long run.

On the other side will it work, yes, smaller tubes will work.

Craig


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## Zapins

Hmm, well, it seems that someone in the neighborhood has wireless internet here in Greece so I'll be able to check my email on and off when we aren't hitting the beaches/sites!

A large tube diameter will make clogging the pipe difficult which makes overfilling the tank and flooding more unlikely. I think I'm going to take bpimm's idea of putting the intake pipe below tank level on the next one I make for my 125g or 90g. Seems less likely to get clogged.


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## bpimm

Check out ebay for float switches, I got mine for under $5. hardly worth messing with building one.

EDIT:
Thay're even cheaper now.
Float Switch


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## addo

One risk with using big pipes is that the water velocity in the siphon part will be slow enough for air to accumulate over time and break the siphon. If you look at the design of overflow boxes used on saltwater tanks they usually have two or tree smaller pipes that carries the water through the siphon fast enough for tiny bubbles to be swept out of the bend.


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## bpimm

addo said:


> One risk with using big pipes is that the water velocity in the siphon part will be slow enough for air to accumulate over time and break the siphon. If you look at the design of overflow boxes used on saltwater tanks they usually have two or tree smaller pipes that carries the water through the siphon fast enough for tiny bubbles to be swept out of the bend.


That is why the suggestion for the barb at the top of the loop, these are only flowing the waste water, a few drips a minute, so the flow will never be enough to stop air from accumulating.


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## Shrimplett

Dang it!!!! I think I have chloramine in my tap water. I was hoping this would work, as I hate water changes!!!


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## Shrimplett

Do automatic water chagers have a valve that you turn when you want to do a water change? Was just wondering because if you could switch the valve, could you add declorintaer derectly in the tank to declorintate the tape water?


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## Zapins

Due to a recent question about the design of an overflow and why I changed the upturned pipe in the main tank to face down I thought I'd include the following diagram to better explain why this will not create a siphon and drain the tank.










A thorough explanation of the above diagram can be found here:http://www.aquaticplantcentral.com/...er-change-system-design-diy-7.html#post726706


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