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Theoretical question about auto top off

2334 Views 17 Replies 5 Participants Last post by  Soothing Shrimp
What device would open and close tubes as needed?

I've been looking at auto top offs and most of them use an electronic float with relay to turn the pump on or off depending on water level.

That's great for one tank.

What I'd like to do is use the idea for multiple tanks.

I understand the pump would most likely always be on and take water from a central water source.

What I need is a controller that says that "This" tank should be filled now that "This" one is done, with some kind of manifold system that opens each hose as needed.

This site has some devices already built. The electronic floats are only around $12 Which would not be bad for me per tank.

I'm dumb as an ox in this area. Suggestions?
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Solenoid valves will work, with the floats opening or closing the valves at the appropriate time. I think the weakness in such a system is the consequence of having either the float switch or the solenoid valve fail. You need a backup system to prevent dumping a lot of water on the floor.
i'll be adding a DIY ATO to a single tank, but my idea for preventing overfilling is the following:

2 float switches. one placed normally to turn the pump on when the water gets too low, and then stop it once it reaches the appropriate height. now, in case this fails I'll have another float switch tied to the first, but upside down, so it's normally on. if the water gets too high this switch will float and cut the power.

so if the first switch gets stuck down (where it would trigger the pump) the second one will flip off and cut the signal.
A redundant system is best.
Maybe 2 floats in case one fails. They both would control the pump & valve.
You'd do a AND && operation


//float1 AND float2 is TRUE
 if(float1 && float2) {
    //turn on pump
    //open valve
 } else {
    // if any float is FALSE
    //turn off pump
    //turn off valve
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"This site has some devices already built. The electronic floats are only around $12 Which would not be bad for me per tank."

I forgot to add the link of the place that has some supplies I'm looking at. Don't know if any of that stuff helps or not?
That is going to get really expensive really fast at that site, especially if you are running them with redundancy. Although, if you have zero fab skills, it might be the way to go.

Lets see if I can explain this clearly enough.
If you aren't concerned about looks and feed the system from a centralized tank that is above everything else, you can vastly reduce the cost. You can mount float valves in the tank that are actually supposed to be RO shutoff valves, they are a couple bucks each. One valve per tank. The (mechanical) valve opens up to top off, and shuts off when the level gets back to the desired height. An electric float valve in each tank ($4-6 each) would serve as a back up. These would all be tied together in series through a solenoid, so that if one tank senses that the level is too high, the solenoid opens. On the normally closed contacts you run some sort of indication, be it visual (light) and/or audible (buzzer, could be annoying for others if you are not around). On the normally open contacts (which are closed when the solenoid is closed. System operating normally) you run the leads for a single solenoid valve that is on the main feed line to all of the tanks. You would have to set a second set of float switches up for the tank to run a pump to auto fill that.
If you are running this directly off of an RO system, you eliminate the need for the tank, pump, etc.
Trouble shooting could be a slight pain if you have a large number of tanks, but shouldn't be too bad. Manual checking of each valve would eliminate the most likely cause (sticking). Electrical would still be simple, just a little more time consuming.
Monthly (more frequently if needed) lift all the valves one by one to test for flow (mechanical float valves) and that it shuts the system down (electric float valves. Visual alarm is sufficient for general testing or each tank, then physically verify that the solenoid is shutting down the feed line).

I think this would have the most simple implementation and be fairly reliable and inexpensive. You could install a cheap switch to bypass the sensor for each tank (or manually install a jumper) to take a tank off line for maintenance or to take it out of service. The only issue that I see would be if you were away for an extended period. A failure of one of the mechanical valves that caused a high level for one tank, would shut down the ATO for all tanks.
Although with a single pump running all the time dead headed would be a higher risk of failing and taking the whole system down, unless it was a magnetically coupled pump.
If you set it up with a pump, you wouldn't need it to fill one tank at a time (with the individual solenoid method). Having each tank fill individually, one at a time, would be overly complex. The demand for the pump by any tank would start it up (pump switch on each solenoid wired in parallel), each tank would actuate individually to fill (its own solenoid would actuate), they would fill in parallel, just at a slower rate. The pump would shut down when there is no more demand to fill.

You could do each tank individually like you said, something in between that and what I suggested where tanks run in banks. You could run redundancy with pumps as well, where if the reserve tank level drops too low, a secondary pump kicks in to fill. You can get as complex and expensive as you want.

I'm assuming that if you are running enough tanks to warrant something like this, you have more than just a few (I'm pretty sure that I recall you are breeding shrimp) and are running a RO/DI system for top off (and making water to specific standards). If the RO system is a permanent install in the room, or in a spot where you could run a hardline, or PEX tubing, I'd go that route and run the ATO system directly off the RO system with one of those small pressurized supply tanks so your fill rate isn't limited to the immediate output capacity of the system (ie 100gpd = .07gpm).

The valves I was talking about are on Amazon. Float valve and water level sensor should yield plenty of results. Some are for RO, others for pools. You will greatly reduce your results by adding aquarium, but you may end up omitting some of the more desirable results. If you go with the in tank float valves, check the dimensions, some of them are rather large and obtrusive.
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Beer, and others, this is making a lot more sense now. I greatly appreciate it- and yepper. I'm a shrimper- hence the need for slow top offs instead of python fills, etc. I figure I could fill a main container with RO and run the pump from that.

Is there a way to draw a diagram? Not too concerned about looks, as much as practicality. I'm a hobbyist and don't have a showroom as such.

I think I'd prefer electronic floats. What type of solenoid would you suggest? And I just plug these in? (Told ya I was dumber than an ox. heh)

I have lots and lots of shrimp tanks for my hobby. Refilling each slowly because of evaporation is becoming very tedious (usually by airline.) I'd love it if this system could refill more than one at a time! I somehow thought that wouldn't be possible, but now that I know it may be- I'm stoked!
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why not set up a constant drip from some tubing?

if you get an IV drip you can control how much liquid drips out. You'll have a lot more fiddling to do, and through out the year, but you've gone from needing multiple switches (maybe even pumps) to tubes with a little rolling clamp on the end.

there is a bit of risk of overflowing, but with a slow drip even I wouldn't be too concerned. I wonder if you could fit a simple float valve on the end of a tube?

do you have pictures of your set up? that may help
Just three shelf racks
I don't really have a way to draw something up and post here.

I was saying a float valve similar to
. They are about 4" long and 1.6" around. Each tank has one (or something similar) set to the desired level. Each tank also has a single electric level sensor like
as the emergency back up.

Running electric level sensors on each tank will require two per tank (unless you are not running it with a back up), plus a solenoid valve, plus relays if you are using a pump to pressurize the system, plus wiring. You are around $50 or more per tank not including costs for the central part of the system. IE: low voltage power supply for the level sensors and relays (low current draw so it will be cheap, you might even have something suitable siting around), pump, container, tubing, etc.
Not sure what your budget is, it might be manageable for you.
My idea had it at less than $10 per tank with the central system requiring a solenoid valve in addition to what was already there assuming it is set up the same way.
Not knocking you for wanting to go the all electric route. I do like the all electric version, I am setting one up for a nano saltwater aquarium using a small air pump to pressurize my RO container (a mason jar). But for me it would be too cost prohibitive for a larger setup like yours.
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Yeah, there's be no way I could do $50 per tank, that's for sure.

$10 per tank is doable over time.

"$10 per tank with the central system requiring a solenoid valve"

What kind of solenoid valve? How would I set that up?
To save a whole bunch of typing...
Are you going to do this directly fed from the RO system, gravity fed, or with a pump?
I'd like a central reservoir by the wall and the pump hose goes in it to draw from, while the exit hose from the pump separates into other hoses leading to one in each tank.

Do I just connect a gang valve to the exit hose and have each hose leading to a manual float in each tank?

Seems like there would be back pressure from the exit hose on the pump once all manual floats are closed, no?

Wouldn't I need a pressure release or something, or is there some way to have the pump turn off when all floats are closed, and turn on when needed again?:confused:
I think that to run it the way you want, and still have a safety, you are either going to need a pump that can run continuously with all the valves shut, or run two level sensors per tank plus the float valve.

One sensor in each tank (wired in parallel) to trigger the pump to turn on, which would have to be set perfectly with the float valve so that the valve shuts at the same time the pump shuts off and is opened when the pump gets triggered. It is doable as long as the float valve has a narrower level range than the sensor, which I doubt is the case. (float valve and level sensor shut off at the same time, but the float valve opens before the level sensor is triggered) Any tank with an open valve would fill before its level sensor is triggered if any other tank starts the pump. This would be fine, but if a tank triggers the pump and the valve isn't open, the pump will run deadheaded, which can over heat the pump and kill it. The other issue is if the level sensor is slightly too high for the float valve. The pump will never shut down, running in to the over heating issue again.
The other sensor would shut the pump down for all tanks if any tank is high.

I really think that gravity fed would be the best option. Unless there is something I am missing, it is going to require an overly complicated set up or a solenoid valve at each tank to control flow into each tank with a single pump.
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"...or a solenoid valve at each tank to control flow into each tank with a single pump. "
Do you have a recommendation on the type of solenoid I would need?
Not one that would be cost effective.

I did think of one way to do it with a pump. You could run the pump on a timer so it cycles for a minute or two several times a day. Feed each tank with a float valve off of a common header from the pump. You can still run a single level sensor to each tank as a backup. The pump will possibly run dead headed, but only for a brief period, so it shouldn't be too much of an issue. The tanks will go low, but only fill when the pump cycles on. You may have to fiddle with it. If all of the tanks, or a large majority, were on the same evaporation/fill cycle, you could run into an issue where the pump isn't able to keep up with evaporation, but adjusting the pump run time, or manually over filling a few of the offending tanks slightly would offset them assuming all tanks have a similar evaporation rate.
It would look something like this

If you don't have experience with the 120V side of things, get some help from someone that does. It is fairly simple in the grand scheme of things, but if you mess it up, things go bad quick.
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Thanks. :)
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