Was running the 1/4" supply line through my sump for a while but abandon because of the pressure drop.

There is merit though in warming the RO. Cutting from here (Aqua-safe) "membranes are flow rated at 77F, 65 PSI and 200 TDS and for every 1F water temperature, the production rate will drop 1.6%"

Has anyone come up with more options for heating their supply water since this thread last posted? I just installed my new RO/DI and I was thinking of coiling about 10 feet of 1/4" supply line and attaching an 8W repti-therm heater to it.

Not sure if that will give me enough time to heat the water much...any thoughts?

Agreed, Definitely needs to be warm... There is a build thread I was watching on another forum, and the guy is in colorado and his RO in line was sooo cold that his RO was produing VERY little water... Was more of a drip that a constant flow.. I think it took him close to a full week to fill 140G tank.

Since this last came up I have taken the line out of my sump. It was just too hard to keep the tank temp up. I looked around for a constant heat supply and decided that my MH ballast would work just fine. My ballasts have the metal fins for cooling. I just ran the water line back and forth under the ballasts. I'm not sure how much my line temp has risen but it's definately warmer to the touch. And it keeps my ballasts a little cooler as well so thats a bonus. Of course it only works during the day but what the heck, it's free heat.:biggrin:

Running through the ballast...a very interesting idea for the future for me. Unfortunately, RO is no-where near my tank right now...so I'm still looking for good ideas.

Tagging along with this one as well since my first RO had very poor performance and I was looking for ways to heat the input. I know the industrial RO unit at the local Exxon/Mobil plant uses steam to pre-heat their lines and the performance is supposedly much better the hotter it is. I was going to use a heat tape (used to keep pipes from freezing) and wire in my own thermostat but looking at my electric bill decided against it:mrgreen:

I ended up doing a 100' of 3/8" RO line and put it in my sump. And worked perfect. I haven't checked the temp lately of the water entering the RO but last time I checked it was around 72-73F. I also did not lose any pressure going into my RO unit.

In keeping along the lines of using the reptile heater...I see zoo med has a heater cable (11.5') at only 15 watts. I could tape this to the supply line and I would get at least 6' of warmer cable. If no-one has any other suggestions...I think this is what I will try.

But, does the sump/tank loose any temp? Personally, with the amount of waste water made, even with the benifits of warmer water. I would think the cost of the electricity to heat the incoming water to the membrane would outweigh the benifits because most of the warmed water just goes down the drain.

Sure it cools the tank.

But if you are like most of us, it is excess heat you need to get rid of. My tank has a total of about 330 gallons, and the lowest I can get my tank down to is about 80F. I have no heaters in my tank.