I guess I'm still a bit confused...so does the float valve on your RO clean water discharge line create enough back pressure to shut the automatic shut off valve? Or does everyone have a pressure tank that then goes to a float valve? Maybe I should sketch a Process flow diagram so it is clear in my head.:wink:

Did the slotted acrylic (with a router but probably a table saw would work) as wasn't sure where I wanted the level. Piece is inside the tank, no pressure on it so the silicone holds it okay.

Was planning on placing a reservoir in the joist space above the sump and gravity feed (even bought a 20g poly tank that ended up being just a little too big so returned) but then the issue was I'd need to remember to fill it up every 10 days or put on a ATO (maybe using a humidifier valve:biggrin:). This works, no wires to short, switches to jam, solenoids to fail open. Have come across on RC where people have flooded their tanks but never seen with a simple 10 buck valve, but with $500 controllers.

As for the membrane, wondering if TDS creep another little misinfo. First membrane lasted around 2 years, more than that on this one. I will notice after many many months a increase in TDS, but change the DI and back to zero.

Output from the ro/di tee'd to the float valve and pressure tank. Ran the unit with tank off and ASOV still shuts the input to the membrane. Did have some problems that ro/di was always making waste even with output off and kept going to the ASOV, ends up was the check valve off the membrane.

Kind of the point, once educated with something far more complicated it becomes simpler because it's the better alternative. But realistically a horse is much easier understand than a car, it's only the surrounding technology that makes the car easier. For example if I send you into the woods with a hatchet, which are you more likely to come back with? A horse or a car?

Yes, but to be clear, I only fill my RO/DI reservoir from my RO/DI filter, and use the same float valve on the reservoir as I do on the sump, the reservoir valve shuts off the autoshutoff valve on the RO/DI input. I only use it to prevent overfills of the reservoir, once full, I shut off the input manually and only turn it on again when it's time to refill the reservoir.

The reservoir in turns feeds a 1/4" line with T's off to each sump I run with the float valves in the sumps. This line is just gravity fed. I also T off this line to my SW mixing reservoir which also has a float valve. So I let that fill and dump the salt in there and have it mixing ready for the next water change.

Running the float valve on the sump right off the RO/DI itself is generally not recommended. I burned through membrane after membrane doing this and when asked about it on the boards (here and others) the answer was that RO/DI's don't do well with constant on/off cycling - whereas a single long runtime is best.

I don't know how Mark is getting away with not wrecking his membranes that way ... more power to him for getting away with it - but for the record this is not really a recommendable approach. Use a reservoir in between at the very least.

Kinda lost me on the first sentence, sorry :redface: What's misinformation?

I'm curious though, do you measure the TDS after the RO but before the DI? The DI will always pull it down to zero if the resin isn't spent. The question is how often do you replace your resin and could you be getting more life out of your resin?

It wouldn't make a difference, the pressure on the float would be the same with or without a pressurized storage tank once the tank is full. The tank is simply an accumulator which stores volume, nothing more. The float will be able to hold the pressure from the RO but in my mind you'd be pretty foolish to hook a mechanical float directly to an RO unit without some kind of safety. This is a big no-no in the hobby and I'm surprised people actually do it. Tony has the right idea if you want to use a mechanical float for an ATO.

ahah Yeah I failed to realize that part. At first it looked like the slot was in the wall of the tank...:redface: one of those days I guess ahaah

I'll agree with you 100% if we can change your sentence to this:
"Sometimes, once educated with something far more complicated, it becomes simpler because it's the better alternative."

:lol:

Mis-information that short cycling eats membranes. Slow death sure and years I find acceptable.

Going off topic here, made me check my notes and do some measurements. -looks like I replaced the membrane Jan 16/07
-last replaced the DI, July /09
-current tap TDS 190, after RO TDS 40, after DI TDS 13.

So bad me allowing my DI to exhaust itself, and yes my membrane is showing wear but it's been 3 years and it's a 100gpd so a rejection rate of only 90% to begin with. Guess I'll change my DI tonight and be good for about another 6 months.

It wasn't misinformation in my case when I replaced three membranes in a row after only 2 months each. And they were wrecked beyond reckoning. Like, input TDS of 200, output TDS of 190. It really stung me since they tend to be about $100 a pop. :( I'm trying to save others from that financial hit when I post about the short cyclings .. I honestly don't know what the difference between your setup and mine is, I'm happy it's working out for you but to be blunt, I don't understand how you're immune to it while I wasn't .. I'm jealous dude.