need help with automated water change

[Siffy]

Ah, so this is a backup to the LM3's programming in case of a failure. What about a low limit float sensor/switch in the sump that would turn off the LM3. I thought the LMs could be run dry without worry. Something is telling me this is over complicated. It's just a hunch.

[activecactus]

Originally posted by Siffy
Ah, so this is a backup to the LM3's programming in case of a failure. What about a low limit float sensor/switch in the sump that would turn off the LM3. I thought the LMs could be run dry without worry. Something is telling me this is over complicated. It's just a hunch.

What about a low limit float sensor/switch in the sump that would turn off the LM3.

Why do that when I can have it on just one latching switch?

[medic29]

Now all of this may look a bit confusing, but I don't think it is when you break it down.

Okay, here is a diagram of what I think you are talking about:

Now in this setup you have the follow:
Tank 1 used to hold RO/DI water and to mix fresh saltwater.
Tank 2 would contain Mixed saltwater ready to be used during your water change.
Tank 3 would be your sump.

Essentially what you have described as wanting is an automatic water change system that begins when you activate it. Then there is a system for filling the mixed saltwater tank when it gets low and while this tank is filling you do not perform a water change.

So the following would be the procedure and what happens:
When you want to perform a water change you press the [b]push button switch[b] (not shown in diagram) once. In doing so it sends power to Pump 3 which then begins pumping water out of the sump and into a waste drain. When the water level in the sump reaches FS1, Pump 3 turns off and Pump 2 turns on and pums fresh salt water from Tank 2 to Tank 3 the sump. This continues until the water level in the sump reaches the level of FS2. When this happens Pump 2 gets turned off. Now the water change is completed and you can push the push button swithch (not shown in the diagram) once to turn the power off to the water change part of the system.

If the water level in Tank 2 drops below the level of FS3 then this activates Pump 1 which begins pumping newly mixed saltwater into Tank 2 unless the water level in Tank 1 is at or below the level of FS5, if this is the case then Pump 1 won't turn on. Now if the water level in Tank 2 is at or below the level of FS3 then Pump 2 won't turn on until the water level in Tank 2 is above FS3.

Now if you thought that was complicated, here is the wiring diagram:

It looks worse than what it really is. I believe this will work. I initially had some logic errors, but I think I have fixed them all.

Let me know if you have any questions.

[kcress]

Sounds interesting!

A few suggestions would be: Push a button once to run the draining and refilling of the sump. All automatically.

Then require a button push to transfer from the new water to the holding tank. If you don't have this stage you could transfer unmixed (unusable), batch into your #2 tank.

I'm also not clear on the purpose of the middle tank if you are mixing in the salt on the first tank anyway? Isn't that redundant? I could see if the first tank was pure water - as a catch basin from a slow RO system or something. Then the second tank would be the mixing and gas equilibrium tank.

[medic29]

It has been said to not use newly mixed saltwater, but rather water that has sat for a day or so. The first tank would also be a tank that would fill slowly with RO/DI and when full would be mixed to make saltwater. One could raise the float in that tank so that it would not allow the pump to pump water out of that tank until the water was mixed...or you could just add a switch there as well. hadn't thought about it that much. This is just something to build on. I have a similar setup on my system. The water change is controlled by a timer and thus the system does 3 water changes a weel.

[activecactus]

Here's a picture of the two buckets.
The first one holds RO/DI water which is used to top of the evaporated water in my sump. I don't want to add more float switches to my sump of fear that it will mess up my top off.

The second bucket contains saltwater or RO water waiting to be mixed, a mixing pump that is controlled independently, and It also has the 2 float switches used to bring in water from the RO bucket. Not seen is a tube that will carry saltwater to the sump via a LM pump.

The wiring diagram for the float switches worked like a charm.
Still not to shure if I can do what I want to do.

[medic29]

If you are using 2 switches in your sump for your auto-top off and it is working fine, adding 2 more for your auto-water change won't hurt anything.

[activecactus]

I only have one chamber in my sump that fluctuates and the Tunze controls that with top off water. If I put switches for the LM along with the tunzes' then when the LM takes out water it will be filled with RO water. The LM only takes out and replaces a small amount of water at a time, 4.5 gallons/week.