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sleepydoc
08/20/2017, 02:53 PM
Does anyone know of a commercially available controller for an RO/DI system? I'm thinking of something that would open a valve after the RO membrane for xx minutes to allow the membrane to warm up to peak efficiency, then close that valve and open a solenoid after the DI membrane, possibly with the entire thing controlled by float valves in the reservoir.

I haven't found anything in my searching, so I may have to DIY it with a 555 timer circuit or an Arduino.

mcgyvr
08/20/2017, 02:55 PM
None specifically for RO/DI systems that I've seen but all that is something a normal reef controller would/could handle..
You could use an ATO system and a time delay relay too.. or roll your own..

Make sure you are ok with an endless potential supply of water to your tank..

sleepydoc
08/20/2017, 03:23 PM
This won't be connected to my tank; it's just for my RO/DI system. Currently I have a Tee between the RO membrane and the DI canister to serve as a bypass to prevent TDS creep. When I want to make some DI water, I open a valve coming off the tee and let water run through the RO membrane until the Post RO/Pre DI TDS settles, then I close that valve and open up the valve coming off the DI resin to start making DI water.

Just looking to automate that process. I have an Apex, but it's in the other room with my tank so I'd either have to run 50 foot cables or get a second controller, but a full controller is overkill for this.

mcgyvr
08/20/2017, 05:24 PM
just need a few relays (ice cube type or whatever) really depending on the logic you want.. 1 time delay too..
or an arduino or esp
http://www.electrodragon.com/product/wifi-iot-relay-board-vdc-based-esp8266/

I personally never worry about TDS creep when filling up decent amounts of water.. Even when I fill 5G buckets I just turn the system on.. I never really notice any negative effects from TDS creep personally.. output is always 0 TDS.. But I don't check TDS post membrane.. Just in and out.. and I get plenty of life out of my DI resin.. That little bit just gets diluted right down..

ravi197699
08/20/2017, 05:26 PM
Here you go, Here is the RO/DI system that flushes the membrane for 18 seconds before it starts producing wate.. I hope this is what you are looking for..

http://www.ebay.com/itm/RO-Reverse-Osmosis-Water-Filtration-System-400-GPD-Auto-Flush-Booster-Pump/131762615134?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2055119.m1438.l2649

der_wille_zur_macht
08/20/2017, 09:46 PM
This is a fun basic logic puzzle.

You basically need three states: 1) everything off, 2) flush line on and main supply line to DI off, 3) main supply to DI on, flush line off.

Use two float switches in the reservoir per the norm, one at the bottom and one at the top, set up to latch. This latching circuit is connected to two relays. The first is a time delay relay with double throw. One side powers a solenoid off the tee between RO and DI (which empties to a drain, this is your flush water). The other throw powers a solenoid between the DI and the reservoir. The latching circuit is also connected to a second (normally open) relay that is between the two solenoids and ground, and acts as a master switch.

This way, at rest, prior to the latching circuit being tripped, you are in the first state. The second relay is keeping both solenoids off. When the vessel empties and the bottom float triggers the latching circuit and powers both relays, you enter the second state. You are flushing the membrane for the duration of the timer. When the timer expires and the time delay relay switches, you enter the third state - the flush line is shut off and the line supplying the DI (and eventually the reservoir) is opened. When the reservoir fills up and trips the top float in your latching circuit, you return back to the first state, everything is shut off.

If you can't find a double pole time delay relay, use a plain old single pole time delay relay with a pair of other relays - one NO and one NC - to get both functions you need.

sleepydoc
08/22/2017, 05:25 PM
This is a fun basic logic puzzle.

You basically need three states: 1) everything off, 2) flush line on and main supply line to DI off, 3) main supply to DI on, flush line off.

Use two float switches in the reservoir per the norm, one at the bottom and one at the top, set up to latch. This latching circuit is connected to two relays. The first is a time delay relay with double throw. One side powers a solenoid off the tee between RO and DI (which empties to a drain, this is your flush water). The other throw powers a solenoid between the DI and the reservoir. The latching circuit is also connected to a second (normally open) relay that is between the two solenoids and ground, and acts as a master switch.

This way, at rest, prior to the latching circuit being tripped, you are in the first state. The second relay is keeping both solenoids off. When the vessel empties and the bottom float triggers the latching circuit and powers both relays, you enter the second state. You are flushing the membrane for the duration of the timer. When the timer expires and the time delay relay switches, you enter the third state - the flush line is shut off and the line supplying the DI (and eventually the reservoir) is opened. When the reservoir fills up and trips the top float in your latching circuit, you return back to the first state, everything is shut off.

If you can't find a double pole time delay relay, use a plain old single pole time delay relay with a pair of other relays - one NO and one NC - to get both functions you need.

Yes - This is exactly what I had envisioned. I was just wondering if it already existed or if I needed to make it myself. It's looking like I need to make it myself.

As an additional modification, if you put a momentary pushbutton switch in parallel to the bottom float in the RO/DI reservoir, you could trigger the system at any time.

I'll have to look at the circuits. I have an Arduino sitting on the shelf that I could also use - of course I'd still need to get some parts to interface the Arduino with the relays, so I might be just as well off building it from scratch.

der_wille_zur_macht
08/22/2017, 07:56 PM
I would skip the arduino unless you just really want to use it. The only "advanced" problem you have to solve is the time delay, and there are relays off the shelf for that. Otherwise it's just a bunch of straightforward logic. Adding a processor won't really reduce parts count since since you still need the float switches and relays and solenoids.

Scrimpie
08/22/2017, 08:02 PM
There is an auto flush system.

Mark Bianco
08/26/2017, 10:50 AM
Something like this? https://www.bulkreefsupply.com/aquatec-auto-flush-flow-restrictor.html

Would this work for your application?

RWEngineer
08/26/2017, 12:22 PM
I would be interested in what you come up with.
I did it with a hi low tank controller then added a delay relay to the output so I could dispose the first 2 minutes of RO water down the drain.

Those of you that have suggested an auto flush kit. He is not trying to flush the membrane.