diy auto top off

I just came back from Walmart, and they have a white trashcan with lid for ~$8 that holds 50 quarts, or 12.5 gallons. I think that might be the perfect container. The AquaLifter can only pull up water a total of 30" of vertical height, according to the pump.

Oh, I didn't mention it can pump 3.5g per hour, so if you wanted to run it on a timer once a day, that may be useful to some.

If the container runs dry, the pump will continue to try to draw up any fluids, but it won't burn up even if it comes up dry.
 
I don't get credit for the AquaLifter idea, but I still think it is a great solution. I haven't hooked mine up quite yet, but will in the near future because I'll be going to MACNA for four days in September.
 
Stile2

Keith, quick question on schematic. Should there be a diode between "Turn On Float" lower float and the "operate" coil. You have diodes on the other float switches and reset coil. Other than that question, I think this circuit is exactly what I'm looking for. Thank you!!

Chip
 
No, no diode is needed on the Turn on float switch circuit.

The reason there are diodes on the Turn off and Shut off Float switches is that I wanted to Red LED to turn on only when the Shut off float was activated. Without the diodes the Red LED would turn on if either Off Float was avtivated.

Thanks I am glad you like the design.

Keith
 
Thank you keith! I see said the blind man!!!

Perhaps you and others could comment on the attached schematic. You will see that I am using the same relay as you. My idea is to control the RO/DI to fill two reservoirs, a "water change" tank and a "Top-off" tank. The water change once filled will just sit until I add salt and the be manually valved into sump as water is removed. The Top-off will be controlled by a peristaltic pump feeding the Kalk reactor and going into sump for top-off. All these will be on timers to control when they are in operation, ie. Kalk during lights out.

I can put circuits together and read some schematics, but my electrical theory is way lacking! I've read here where it is advised to have a Diode and Zener across the coils. Would that be both coils on a dual coil relay? For diodes, would a 1N4001 or 04 be better. I've got a bunch as well as 1N5400 sitting around. Also, for this application, is a 1N4742A the right zener?

Please feel free to critique this schematic. I won't take it personally, otherwise I wouldn't put it up. Thanks for you insight and help!!

Chip

98490Topoff_Schematic-med.GIF
 
First let me say that I'm a newbie at the electronics as well.

My Dad works with a guy that designs the wiring for airplanes and he checked my design and made one correction.

I do not know what the difference between diodes are, or what a zener diode is, so I can't help there, sorry.

But I can make the same correction that was made on mine.

You have a resistor and LED on the coil circuit for both relay. What will most likely happen is the resistor will drop the current to the point where it will not activate the relay.

That is why in my design the Red LED runs in parallel to the coil with a diode to stop back current.

Also and maybe I am not understanding your application, but as it is drawn the RODI Input solenoid will activate if either relay is Operated. If the top relay is operated then both Top-Off Tank Solenoid and RODI Input will turn on, and if the bottom relay is Operated then the RODI Input and Water Change solenoid will turn on. Is that correct?

And be careful your LED are drawn backwards, I think, the flat side has to be on the negative.

HTH
Keith
 
Understand your comments on LEDs. I will change to run parrallel as well as add a diode to block back feed. I think you're also right on the LED position, probably are backwards - I'll flip.

As far as operation, you are correct. I want the RO/DI on when either tank is asking (float switch) for water. I may also put a mechanical float on the tubing as a backup (haven't decided yet. By my estimation, once the water change tank is full, the RO/DI will only come on to fill the top-off tank. Then water change, and the tank will start to get refilled again for next water change.

Chip
 
I've been reading post after post about a DIY Auto Top Off and was 99% ready to buy an off the shelf product. BUT, after talking with my Dad who works with electronics he and I built a schematic. I have not posted it until this time as I wanted to build it to make sure it worked first.

My goal was to have a system that used a single float switch to control water level in the sump. The fresh water storage could fit in the sump and not overflow it, so other than a small salinity drop, I did not feel the need to have a second backup float switch in the sump. The res is manually filled. There are two float switches in the water top off (res in the diagram). One is to prevent the pump from coming on if the res is too low and the other is to trigger a buzzer to let me know the res is low.

The schematic is below. I added a detailed explination on the Relay, since that was the hardest part for me to understand. Hope this helps someone. Feel free to comment/question.

auto_top_off.gif
 
Chrisguy,

I made a top off switch similar to your drawing. The problem with this setup is that a small wave in the sump will cause the sw to toggle; the wave makes frequent switching cause my pump to go bad after a month in use. I'm going to redo my top off sw using the stile2's latest drawing, w/c would eliminate this problem.

xinu
 
What the diagram does not show you, which I believe is a good practice for anyone using float switches, is the 1 1/4" cap and small piece of 1 1/4" PVC that suround each float switch. The cap has holes to allow the water to raise and drain (relieve air pressure). The PVC prevents the "waves" from affecting the switch. The amount of turbulance will determine the length of PVC pipe needed. Most people will do fine with a 2" or slightly longer piece. If needed you can also add a filter to the bottom to prevent snails, fish, etc from affecting the performance of the float switch (holding it down).
 
Hi Chrisguy,

I think in my aquarium setup w/c evaporate about 2.5g a day can cause small water drop every now and then, this too causes the switch to toggle often. But I like you suggestion abut housing the sw inside a pvc.
 
Another option is to put your pump on a timer, something like on for 5-minutes every 4-6 hours. This will also help with the constant on/off cycles of the top off.
 
Chris,

Nice simple design. My design is really for direct RODI hookup.

One thing I would watch is the LEDs. You will need a resistor inline with the LED to pull the voltage down, but in the Red LED it will probably pull it down enough to where it won't activate the buzzer. You could run the LED parallel to solve the problem.

Keith
 
Keith - thanks! I bought 12VDC LEDs that have a built in resistor. They also mount nicely to a project box.

I basically did this with blind confidence, but good old Dad helped with the details.
 
Do you have any pictures of this built yet? It seems like an easy design to follow and build. What about the float switches, can the ones from autotopoff.com work with this?
 
Should be able to. AFAIK, most float switches are universally usable in these types of applications as they are really nothing more then a standard switch... One wire in, one wire out.
 
I went to buy a relay yesterday at Radio Shack, but quickly realized I had no idea what kind to get.

I'm using a float switch in my sump, and I happen to own 6v power supplies, but odds are I have to but a 12v powersupply right? How do you know which relay to buy? The pump I'm using is an Aqua Lifter, and it only used 3w or power. Of course, I'd like to keep my options open if that device breaks, so I can run a small powerhead instead.
 
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