I hope this topic isn't too controversial .

Just thought I'd share my latest trick.  I just got an RO/DI unit so I needed a way to automate the tank topoff.  My old single float switched to a refilling powerhead just wouldn't do here.  Here are the parts I used.

This a picture of the solenoid valve.  It's powered by 120v AC.

Here's the relay and socket:

Here's the two floatswitches in a diy adjustable holder:

The concept behind it isn't my own.  It's very common in industry when controlling levels to set up two switches this way.  It's called a "pump up" scheme.  What it is, is two floatswitches wired through a DPDT relay with one of the contacts operating the solenoid.  When the water level drops below the lower float, the solenoid is tripped and RO/DI water flows into the sump.  When the water level fills high enough to trip the upper float the solenoid shuts off and is reset.  This method of control is preferable over a single float because with a single float the solenoid valve would be constantly coming on and off.  With this method the solenoid only comes on a couple times per day.  Also it's better on the RO to run continously rather then in short bursts.

The solenoid is plastic bodied from http://www.mcmaster.com - www.mcmaster.com part # 7877K23:  $17.18

The relay and socket I got from Standard Supply in SLC:  $10

The floatswitches from http://www.floatswitches.net - www.floatswitches.net  : $15

Acrylic I had laying around, the RO line connectors from Home Depot.  All in all, I think it ended up costing about $50.  It works like a champ!  Here's a few pictures of it installed.

The relay:

The solenoid valve installed:

The float switches in the sump:

there you go again, just inventing all kinds of ****

looks good, let us know how it works

Thanks guys.

Marcus, it's worked great for the last few days.  I'll be sure to let everyone know if it gets my carpet wet.

Shane, I think this setup would dose a little too fast for my liking.  And my kalk reactor would need to withstand RO pressure (30 psig?).  I like the idea of a controlled flow dosing using a dosing pump.  Nice and slow.

Jon, of course, fantastic job! Your DIY skills are unmatched. Just a thought on the floats and overcycling the solenoid. Somewhere, and I cannot remember exactly where but I will look, they make a float switch with adjustable travel so that you wouldn't need an extent type system with reset. Basically it allows an increased or decreased travel in the float which is on a switch. Not that your method is bad because it's great, just advising of an option that I use at work.

Again, great job!

Carl, if you find any info online regarding the way you do it let me know.  Or we can talk about it next time I see you.  I'm always looking for better methods. 

The other scheme I looked at was to use one solenoid and a timing relay so that when the level tripped the float, the solenoid would stay on, even after the level had increased, for an additional 10 -15 minutes.  It just turns out that a timing relay ($20) is more money then an extra float switch ($6) and DPDT relay ($6).  Being cheap, I went this route.

Jon, I will see if we have an extra mechanism laying around as well. We'll talk about it next time we see each other.

I think that I can find it cheaper, but just to give you an idea... http://www.grainger.com/Grainger/productdetail.jsp?xi=xi&ItemId=1613544591&ccitem - http://www.grainger.com/Grainger/productdetail.jsp?xi=xi& ;ItemId=1613544591&ccitem =

Jon - have you had any problems with this design now that you've had it running for a while?

Sean,

Crazy I was just thinking about this as well.

Adam

No complaints at all.

The solenoid only comes on about 2-3 times per day (really cuts down on ON/OFF cycles, extending the life of the valve).  I've had the system "malfunction" twice due to chitons, but without any serious problems.  That is a fairly common problem with float switches (probably not as much a problem with a float valve).  What happens is those really small chitons (4-6 mm long) get on the center post of the float, but under the actual float, when the float is submerged.  This doesn't allow the float to drop when the water level drops and the valve doesn't come on resulting in the sump level dropping (no make-up).  No worries about wet floors, just dry sumps.  I've caught it both times before it went dry.  My sump can go probalby 3 days without make-up water before the pump will suck air.

Even though I still haven't found time to build a kalk reactor I still think this is the best/safest set-up for it.

Jon,

You have Chitons?  Where did you get them?

Jake,

Not sure where Jon got his.  Don't know of any local store currently selling any.  But they retail online for $2 so they can't be that hard to find.... well maybe they can be.

Adam

hmm... perhap I'm confused.

They're very small (3-6 mm long) with a shell on their back that looks like an armadillo.  Are they chitons?  They just came with the live rock and they're everywhere... I see them in almost every tank I've ever seen.

Here is a picture of a chiton.  Although not all are as colorful as this one.

http://www.birdsasart.com/red%20Chiton.jpg -

Here's a picture (Adam, you can have it if you wish).  Is this a chiton?  The brown circle is a penny used for size comparison.

Limpet.

Adam

Definitely a keyhole limpet.  Suzy has been looking for some.  I gave her a couple, but I'm sure she could use more if you want to part with some.

BTW, I caught some of them eating my Solitaryensis!

Yes... I could have swore that a few months back I pulled out a segmented shelled mollusk (did remind me of an armadillo), but I must have been dreaming.  What I have is obviously limpets.

Why are they called Keyhole limpets?

Here's a wiring diagram.

Ah ha!  I was beginning to think I my memory was failing me .  I found this guy in my sump last night.

Yep, chiton.

Adam

Awesome,

Do you have a lot of them?

Jon- just thought of a funny story.  Back in high school when we studied these it was always funny to hear people ask questions about these things.  It was really funny to listen to the girls in my class because they acted more embarrased than the guys did.  No one knew how to pronounce the name and they would ask quesitons like "what do ****-ons eat?" or a girl would quietly wisper to the teacher (like it will still allow her into heaven) "um, Mr. Bender.... can ****-on's breath out of the water". 

Man oh man did I sit there laughing away.  For those of you who don't know it is pronounced Ki-tun. 

Adam  

Re: Chiton's...  I don't have many.  I just remember the first time my float stuck I found a "potato bug" was in the way.  The vast majority of little guys in my sump are limpets.

Re: Wiring Diagram...  Do you have the exact same relay that I have (Bugzme, do you know if all relay terminals are numbered the same?)?  If so, I can tell you which wire goes to which terminal.  Otherwise, I'll have to talk you through it another way.

Suzy, you can have every limpet in my sump.  If you need them before the next meeting you'll have to stop by the house.

Jon - just wanted to thank you for this idea and showing me how to do the wiring.  I just finished building the float switch and it works like a charm.

Today was a good day - I built the float switch, probe holders, and got the reactor going.

wanna build me one that I can just plumb a hard line too? I'm too buisy to be creative. I'd put a on off valve on my main line cuz I don't have a holding tank (5g bottles) Then run a perminent hard line to my sump where it could drip untill full. It takes 5 g 5 hours. No biggie. But then I could open it when I needed to fill my bottles for other tanks. Even if it had to fill say 3-4 inches in the sump at a time I'd be ok with that.

anyone? Or do i get an AC/toilet float

 I'm a block away. Where in the store? I'm there usually once a week.  

thanx though

Resurrected.

Jon,

I am sure you have probably thought of this, but, would a guard around the floats keep the chitons out? 

John G.

Great idea Corey.

If you are using just one float switch then wire like this:

Valve connected to screws: 3 and 8
Float connected to screws: 7 and 5 (there is no polarity on the switch)
Power:  common to 8, hot to 5 (it'll work vice/versa but it's better to do as shown)

I use two float switches to maintain my level within a "dead band".  If you want to do that then wire like this:

Valve:  3 and 7
Low float switch:  4 and 8
High float switch:  4 and 5
Power: common to 7, hot to 5
place a jumper between 6 and 8

Viola... be sure to dry test it before installing it

That is an absolutely fantastic idea by Corey, and great work Jon.  I really enjoy seeing that.

Adam

Thanks Adam.

I might add that I wouldn't use a relay with just one float switch.  I'd wire the the hot to one side of the valve, common to one side of the float, then connect the other float wire to the free valve plug.  The solenoid in the valve does not draw enough current to be of real concern.  Although I might wire a resistor and capacitor across the switch like this:

I'm not an EE, but I'll give it a try.  The inductive load (in our case a pump or solenoid) is kinda like a wound up spring.  When the power is turned off it uncoils and releases all that stored power.  This can cause severe arcing in the reed switch which can ruin it.  The cap/resistor  act like a big cushion and dampen the release.

I think you can get them at radio shack.