Single Push Button Automatic Water Change Setup

  • #1
I am planning to build water change setup where additional smaller tank is used to pull tap water, prime it and dump into main fish tank with single push of the button. With such add-on daily WC would become easy where the only thing I do is to push a button and observe wc being done automatically. This is something else from my past continuous WE (water exchange setup I had running for over a year at my old place). This one primes tap water instead of filtering it through expensive active carbon coconut filter system which require often filter changes.

Being engineer for living I designed the concept system on a piece of napkin and actually started to purchase parts for assembly, however I thought about sharing this progress with those of you who might be interested.

So here is how it started. Read it in next post.
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  • #2
Imagine your own existing fish tank. Then imagine additional smaller tank (called WCT) installed next to it or hidden in the closet.

The WCT has to be filled with tap water, then primed (using Seahem Prime for example) then stirred and finally dumped into main fish tank. Oh, one more thing, the main tank before this step would have to be emptied partially with amount of water equal to WCT volume right?

All these steps are done by most of you who do manual wc changes. So the idea is to automate it.

Looks like, all we need to do to make it work is to :
1. connect WCT to tap water source (fosset)
2. connect main fish tank to WCT to enable new water transfer
3. connect main fish tank to drain to remove old water

Looks pretty simple. Now here are few additional things that need to be installed to make it happen automatically:
4. Valve on the tap water input to enable filling of WCT
5. a Pump to transfer primed water to main fish tank.
6. a second Pump or overflow to remove old water form main fish tank.

In addition, we are going to need :
7. water level limit switches used on WCT, one to prevent its overflow and second to sense WCT being emptied after transfer is complete to end the entire wc cycle.
8. controller to run all this
9. and pf course title "pushbutton" to start the wc.

So far, so good? Read more in next post.
  • #3
You don't need to mix prime if you add prime before refilling.
I wouldn't use faucet directly, I'd use a tee underneath the counter. Ive though about this but don't have room for tank or water source/drain anywhere near tank.
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  • #4
You don't need to mix prime if you add prime before refilling.
I wouldn't use faucet directly, I'd use a tee underneath the counter. Ive though about this but don't have room for tank or water source/drain anywhere near tank.
Well, good thought about adding primer before filling WCT. But are you sure prime won't deactivate/use itself up before entire WCT is filled? Something to check and validate anyway.

Not sure what you mean by tee under the counter.
  • #5
Prime is fine adding before water. The water line under counter goes to the faucet. Tie into that instead of an adapter or rubber attachment to faucet end.

I'm actually considering hooking my lights, co2, temp and pH to Alexa so she can report status and turn everything on and off wirelessly.

For the water change system, it may be cleaner to use electronic sprinkler valves so you only need one line in each tank. The valves can reverse flow, etc. And you'd only need a single pump.
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  • #6
Oh yes, there is lots of parts I have not detailed yet, including solenoid driven water valve for example.
I will get into it next. Please be patient, thank you.
  • #7
Sounds interesting. Can the button be a red button?
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  • #8
Sounds interesting. Can the button be a red button?
LOL, nope Red is to stop in emergency, Green will start.

Pictures coming soon.
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  • #9
This weekend I started to build the plumbing for the subject system.
I decided to use 1/2in pvc piping readily available at local home improvement stores. This allowed to keep fairly small drill size when going through the walls (7/8 in).
I started from feed line. I used washer fosset which I spit to have branch for the fish tank. A standard 3/4 Y garden hose splitter did the trick. Right after splitter I installed solenoid shut off valve which later will be hooked up to plc controller. From here it's just half inch pipe right to the tank.



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  • #10
At this point I can feed the wc tank manually by engaging solenoid shut off valve by plugging it into the outlet. Later it will be driven by plc controller automatically.

Next wast the drain line to remove water from main tank. For time being I used manual shut off valve to close line when draining is complete. In future it will be replaced with solenoid valve similar to one installed on feed line.
Because the drain line is always primed, all I need to do to drain some water is to open valve. I have my drain line going outside the house directly to my backyard garden. I am sure my plants appreciate every drop of water coming from the tank. So nothing gets waster. Living in SE Florida I have no worry about pipe freezing in winter season which also simplified the entire setup.

I used leftover drain flex pipe from old Fluval 306 filter.


The flex pipe terminated with rubber fitting fits perfect to standard half inch coupling. No glue needed.


The manual shut off valve is in the closet. The other end of this pipe (not shown) protrudes external wall and ends up outside in garden. All passes are sealed.

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  • #11
With all piping done, next week plan is to install limit switches, transfer line (to transfer water from wc tank to main. And hookup shutoff valves to plc controller.

Btw, with presently installed partial setup I already see advantage. I no longer have to drain main tank using buckets or garden hose. I just open drain valve and water deans itself using gravity and fact that drain line is always primed.

I also no longer have to use buckets to prep new water. All I do now is plug in solenoid valve on feed line and want till wc tank gets filled. Then I add prime, stir and transfer water from wc to main tank using small fountain underwater pump I purchased along with plc controller. I use flex pcv tube to transfer.

Works great. No mess. Can't wait till next weekend.
  • #12
Very cool. My wife would shoot me if I drilled holes and ran PVC around the house!
You could install underground sprinkler distribution drip system which would reduce evaporation and evenly distribute water.. for the following weekend of course
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  • #13
I had drip system for almost two years. It worked but it was expensive in maitnaning (cost of coconut carbon filter) and still had a risk of chlorine poisoning.
And most of all it was quickly developing biomass due to relatively slow water slow which was causing increased levels of nitrites.
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  • #14
Today I added check valve on transfer pipe to prevent water from main tank returning to wc tank. It's 1/2 inch valve I got inexpensively on amazon.


Here is a view for upgraded fitting. What you see is view for wc tank with submersible pump installed on its bottom used to transfer primed water to main tank. Right above its outlet, a check valve installed and return pipe right into the tank.


I used old discharge pipe from my older Fluval 206 filter I no longer use. Works great.


I still wait for proper water level sensors to arrive to have my controller hooked up and configured to get subject single button operation. Here is PLC I am going to use.


In the meantime, I received two additional solenoid valves. One smaller for use to dose Primer into the wc tank.


Second larger valve (identical to intake valve I have installed on incoming water pipe) to be used for opening siphon on the discharge pipe for the main tank.


To be continued.
  • #15
I like it... I was wondering how you were going to dose the prime. With a valve like that, I'm guessing you will have a diluted prime solution in distilled water or something with a pump?
A better approach may be to use a syringe hooked up to a slow motor and gear. Each 1 second of operation would administer 1ml of solution for example... You could even work up a diluted solution for the syringe.
This is how they dose formula/medicine for infants in ICU for example.
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  • #16
Yes, the valve will work, with some addition which is coming. Be patient please, thank you.

BTW, the picture does not do justice, this walve is really small. It's 1/4in NPT.
  • #17
But, prime is generally measured in ml amounts.. without dilution, 1/4 is way too big for any controlled dosage amounts.
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  • #18
It will work. Wait till I finish, thank you.
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  • #19
Today I completed assembly of basic version of my subject WC system.

After programming PLC, I have achieved 1st stage out of three planned of implemented functionality:

1. Pressing GREEN button starts the process, which is tap water intake
2. Water is taken until top level switch trips. Then intake valve closes.
3. Once 2 happen, mixing pump starts automatically.
4. Adding PRIME to mixed water is still manual at this stage (will be automated in final version).
5. Once prime is added and mixed in wc tank, pressing GREEN again starts conditioned water transfer from wc to main tank.
6. Transfer stops once tank is empty (low-level water switch trips).

Below is my prototype controller setup.
From left:
- button panel, GREEN starts process step, RED button is to cancel entire process anytime (STOP/CANCEL button)
- PLC (programmable logic controller)
- three controlled by PLC output mains outlets: one for intake valve, second for mixer pump and third for transfer pump.

In next 2nd stage, I plan to add system extension to control second discharge valve to remove partial water from main tank, something at this stage I do manually by cranking valve.

The 3rd and final stage would be to add automatic PRIME injector step which would eliminate manual dosage. Adding this function will also eliminate 2nd button press.

I also think about adding a safety loop to stage 3 to detect chlorine presence in wc tank before transfer; and prohibit transfer in case traces of chlorine are detected.

In case of problem, the alarm in a form of tower light and texting my cellphone and finally connecting PLC to internet to enable remote water changes when I am away will be my version of cherry on the top.

Details and YT video of working system coming soon.

  • #20
Pretty cool. How would you detect chlorine automatically? Camera with an alert hanger?
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  • #21
Pretty cool. How would you detect chlorine automatically? Camera with an alert hanger?
I am thinking about it. Not even sure if that's possible, research still on "to do" list.
  • #22
Honestly, if you get the prime dosing reliable, you shouldn't need to worry about it. Nobody tests the water after treatment.
Also, your PLC unit looks nice, but wouldn't an Arduino with relays be cheaper and easier to hook to the web?
I used one to create a wireless control for 64 zones of Christmas lights driven by computer and pair of xbee modules.
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  • #23
Nobody tests the water after treatment.

Well, I do test unless I do treatment myself by hand. Even then I do test randomly from time to time.
Nothing auotmated is reliable 100%, cars, even spaceships. So testing is good and obvious choice when it comes to living stock of fish which I keep and care for for years.

Also, your PLC unit looks nice, but wouldn't an Arduino with relays be cheaper and easier to hook to the web?

Sorry mate, but as pro, I use pro equipment. And you are right, Audrino is great when I want to do Christmas lights, not my fish. Cheers.
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  • #24
I have moved to next step of my automatic wc system by adding two way drain setup.

With this step I added two ways to drain my tank:
1. by opening drain pipe solenoid valve; the water will drain as long as valve is open or water level drops below drain intake basket.
2. by overflow, installed in the tank.

I use method 2 for frequent daily wc where I replace 30 gallons at one time. This method is stress-free for fish as they do not see water level change.

Method 1 is used occasionally when I do larger wc changes above 30 gallons at the time, usually for 50% wc.

Installing setup for 2 required only installing overflow and plug it into the drain pipe. And priming the hob U and drain pipe.

Setting up for method 1 required installing additional solenoid valve which is controlled by PLC in draining step of programmed automatic wc method 1.

All took me about 30 minutes to install plus time for setting up the pvc glue.

Pic below shows additional setup to be added to existing drain pipe.


and installed, note pvc fittings match perfectly Fluval rubber terminators on the black drains. Left pipe is for method 1, right for overflow 2. Drain pipe is on the right.


I see standard Fluval filter drain for draining in method 1. No. 2 shows overflow.


amd same look but under water during wc with partially water drained with method 1.


I truly enjoy "bucket-free" and "hose-free" wc, it is great time and effort savier. And allows me to do regular water changes without skipping schedule to keep best water quality for my fish. It also ensures spill-free wc which my family members, specially my wife appreciates. No mess.

Next upcoming step is to add and automate Prime dispenser.


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  • #25
Last week I added final 4th output to my system ("D") and connected existing electric drain valve to the PLC. So far system have been using overflow and additional direct drain valve was used manually whenever I wanted to drain portion of water before adding new.
With PLC controlling drain, I no longer need to flip its switch manually. PLC does it automatically whenever cycle is started. The overflow became just an safety preventing floor flooding in case. something in the system breaks.

Also, the heater has been plugged into same output which controls mixer ("M"). This way when auxiliary tank gets full the heater comes on along with mixing pump bringing water temperature to required level. When water transfer starts, heater gets turned off automatically. Note , heater has built in thermostat.

Daily wc's of 30 gallons are quick effortless routine and fish seem to love its consistency.


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