A little automation is definitely nice!

[Anonymous]

Now I'm well aware of the potential perils of automation, but man it is nice even if it's just a little thing.

Story: Needed a new RO membrane, ordered some extra filters, figured I'd give a booster pump a shot as well since my water pressure is a little on the low side (very low 40s) but I saw one with a few extras for the same price, those extras a solenoid switch + pressure switch.

Now let me tell you making fresh RO/DI water is a chore, not so much because it's hard work, but I turn the water on, let the garbage can fill, and HOPE I remember that it's on before going to bed (forgot on more than one occasion).

Well I happen to also have a floatswitch sitting around as well, and while they are notorious for creating disaster inside of a tank due to salt creep, snails, etc, I figured my RO reservoir will be fine. Replaced the pressure switch with the float switch (no pressurized tank), and hooked the solenoid up, and turn on the water and wammo! Instant water making! I don't even have to touch anything, when the water level isn't at the top the float switch has the circle closed (i.e. power is running) booster pump flips on, solenoid gets power and opens up to allow water in, pressure raised to about 70PSI and 75gpd membrane seems to actually do that now! When water gets near the top, float switch rises opens the circuit, booster pump turns off, solenoid snaps shut, so water stops to the ro unit, and all is good!

I know it's a silly thing to be happy about, but water changes will probably be more frequent now since I have a full supply on water on hand, I don't think I'm ready to an auto top off for the tank as I am a tad scared about that potential "unlimited" supply of freshwater going into the tank. But it's the simple things in life that make one happy, and this simply thing has made me happy.

Even if you don't have a booster pump, if you're making RO/DI water like me a float switch + solenoid valve is a good investment.

 

[Anonymous]

Mike, you're aware of what membrane creep is right?

 

[Anonymous]

I'm going to say no... simply because google sucks at giving me an answer right now other than all these products which help minimize membrane creep.

So school me Mr. Matt.

 

[Ben1]

Now let me tell you making fresh RO/DI water is a chore, not so much because it's hard work, but I turn the water on, let the garbage can fill, and HOPE I remember that it's on before going to bed (forgot on more than one occasion).

lol my kitchen ceiling is held up by 2x4's right now. I installed a chiller on my sons nano last night since it was in the 90;s here but did it pretty late like 1:30 am. SO then I decided to make some top off water and fill it up, I let it fill a bucket for 30 minutes and at 20 am I went in toped off the tank with what was in the bucket, took the ro line dropped it on the floor and went to bed lol....

My son woke me up to, hey Dad someone forgot to reconnect the RO line. When I went downstairs my kitchen was raining...not a good thing.

Anyhow my tank is topped off by a LM3 and the RO unit fills a old 5 gal salt bucket I put a float vavle on so its always full.

I would be hesitant to use a float switch or valve to fill the RO/DI reservoir because of the poor quality water production associated with membrane creep. Doing it manually is probably a bit of a pain, too. What you may consider is hooking up a water timer valve to open up the valve for longer durations, and couple it to a float valve inside the reservoir to ensure it doesn't overflow the reservoir.

Gilmour makes a really good quality water timer valve that you can find at Lowe's.

Matt wrote that in another thread but I have been using the float valve in the bucket method for a while and I am a bit lazy in changing things. :lol:

 

[Ben1]

FWIW, IIRC my understanding was that membrane creep was when the RO/DI first starts, for a few minutes it lets through a higher TDS water and so if its on a float valve and constantly turning on and off to keep the bucket full you are always getting that creep in the supply water. But I am sure Matt has a better explaination

 

[Anonymous]

Shouldn't the DI take care of the creep?

 

[Ben1]

I think that is part of the point to, you end up burning through DI faster.

 

[Anonymous]

Ok a bit of research, and using the term TDS creep instead yielded a bit of a better result. It does in fact seem that when the water is "zero" you might get some creep, I still don't understand the mechanism why but whatever. However it seems that this creep is amplified when you're constantly turning on/off your water making process as opposed to letting it run continuously. And yes your DI resin will take care of it of any creep that does pop up, sure you go through it faster but I'd be curious how much faster.

This being said however I really don't know how this applies to me at all. I fill a LARGE amount of water at once (relatively speaking) 30 gallons or so when I do a water change, if I'm doing a water top off, then 5-10 gallons a time between my two tanks. So the on/off/on/off issues associated with a "infinite top off" (i.e. every drop that you evaporate you put back) is not what I'm doing. I'm still manually getting a bucket of water to top off (my system is large enough that an injection of 5 gallons of freshwater isn't going to do much to change the salinity).

Although this being said, sounds like another reason not to have an auto-top off on the tank proper

 

[Anonymous]

Great! I just mention it to alleviate any anxiety about introducing RO creep into the tank.

 

[Anonymous]

Although this being said, sounds like another reason not to have an auto-top off on the tank proper

No way! Fill a large container and use it for auto top off! Fill it once a week and you are gold

 

[Anonymous]

Shouldn't the DI take care of the creep?

Theoretically, yes, but apparently there are issues with running short spurts of water through DI resin too. If the flow isn't maxed out on a regular basis you can get channeling through the resin beads and it shortens the actual lifespan of the filter.

This is according to the Siemens guy that maintains our big DI filters, but I'm assuming the same issues exist with smaller ones.

 

[Anonymous]

Ok a bit of research, and using the term TDS creep instead yielded a bit of a better result. It does in fact seem that when the water is "zero" you might get some creep, I still don't understand the mechanism why but whatever. However it seems that this creep is amplified when you're constantly turning on/off your water making process as opposed to letting it run continuously. And yes your DI resin will take care of it of any creep that does pop up, sure you go through it faster but I'd be curious how much faster.

Not sure, but it'd be simple enough to run some tests and find out.

This being said however I really don't know how this applies to me at all. I fill a LARGE amount of water at once (relatively speaking) 30 gallons or so when I do a water change, if I'm doing a water top off, then 5-10 gallons a time between my two tanks. So the on/off/on/off issues associated with a "infinite top off" (i.e. every drop that you evaporate you put back) is not what I'm doing. I'm still manually getting a bucket of water to top off (my system is large enough that an injection of 5 gallons of freshwater isn't going to do much to change the salinity).

Although this being said, sounds like another reason not to have an auto-top off on the tank proper

Yup! I wasn't sure based on your first post how your topoff was set up. Sounds golden!

Hey, if you want to monitor your water quality on a continuous basis you might look into these Water Quality Indicator Lights. I can't vouch for this brand or any other but they do work well. A small probe measures the conductivity and the light goes off if it goes above a set value. You place them in line in your plumbing, usually after the RO membrane and after the DI resin, or do 2 DI resins with one after each. Or you could just buy color changing DI resin, but these are more fancier and gadgety.

 

[Anonymous]

Well I have a couple of inline TDS meters, but it seems everytime I get some sort of reference solution it's not the correct kind that I need. Latest calibration was I used my tap water, and someone who services tanks to calibrate against his equipment, so I hope that works out as far as that goes. Just need to really MacGyver in a hardwired system to power them, those little watch batteries die so fricking quick.

 

[Anonymous]

Thanks Matt. That makes some kind of sense about the channeling.