Is this a good idea?

rdnyva

Active member
After having tracked my horrible brown hair algae back to a bad DI cartidge and TDS of 15 I want to safeguard aginst this happening again. Right now my top off comes directly from my rodi filter through a float valve and into my sump. I'm thinking about getting a 44 gallon trash can and putting my top off water in there, then run a line to the sump. This would also solve another problem: dosing limewater. Instead of using 1 gallon jugs twice a day (PITA) I can mix up 44 gallons at a time. Opinions and other options please.
 
I think it is a great idea. If your float switch should fail, it would continue to add freshwater to your tank. Left unatended, this would ended up killling your tank.

My RO/Di runs water into a 30 gallon garbage can with a float switch. Every 2-3 days I take five gallons of that, add lime and pour it into a top off resivour, connected to a float switch.
 
The configuration you suggest is better than hooking the system up directly to a float in your sump. A meschaefer said - if you have your RO hooked directly to your sump, and the float valve fails, the system will just keep pumping and pumping and could cause significant problems re salinity levels in your tank.

Some suggestions:
Elevate the DI water reservoir so that it can gravity feed to the float in your sump.

Size the reservoir so that it is about 1.1 times the amount of top off water you need in a week. That way if the float fails, you've automatically limited the amount of fresh water that can enter your sump, and you've minimized the frequency of needing to make pure water to once per week.

Because you are going to make pure water only once per week, manual controls on your rodi system are fine. You won't need an automatic shut off valve.

Think about extending your waste water tube to the washing machine, and plan on doing laundry at the same time that you make pure water - viola - no waste water.

Russ @ BFS
 
Thanks guys for the input and advice, much appreciated. I am going to give this a try. I like the idea about sizing the reservoir to about a week's worth of water instead of getting the biggest trash can I can find, Good idea there. And BTW all my waste water goes to the pool, so it's not wasted.

My one other concern is that my rodi and subsequently my top off trash can is located in the garage. I run 1/4 tubing through the garage wall, along the baseboard in the living room about 12 feet, that is no problem. I'm not concerned about fumes becasue there is very little traffic in and out, we move the cars (2) about once per day or so, and the garage door is almost always open. But since we live in Florida the temps can get quite high, especially in the summer. Do you see a problem with about 2.5 gallons a day of water in the 90's (and it's probly lower than that considering it's not in the sun and it's cooler at night) going into the tank. I don't think that little amount of water going into a 200 gallon system would be a problem, but I'd like your opinion. Thanks again.
 
If you have 2.5 gallons at 90 degrees, and 200 gallons at 78 degrees, the weighted average comes to 78.15 degrees. And that assumes that there is no other mass (e.g., rock, sand, glass) to buffer the water change.

So no - nothing to worry about this set up changing your tank temperature much.

I'd give you a different answer if you were asking about water changes.

Feed water at 90 degrees will reduce the rejection rate on the membrane a bit, but probably nothing to be too concerned about.

Keep a lid on your water revervoir, and watch for algae growth in the system.
 
rdnyva

What kind of pump do you have pumping from your garage to the sump? and what kind of auto top off system do you have? I'm looking to do the same thing but my water will be in the basement.

Have you noticed that your TDS has gotten to 15 pretty quick. I pump my RO/DI right to my sump and was told that the constant call for water, but in very small amounts creates some kind of membrane creep, which means the membrane is used up sooner than it should be.
 
<a href=showthread.php?s=&postid=8338661#post8338661 target=_blank>Originally posted</a> by scholl
rdnyva

What kind of pump do you have pumping from your garage to the sump? and what kind of auto top off system do you have? I'm looking to do the same thing but my water will be in the basement.

Have you noticed that your TDS has gotten to 15 pretty quick. I pump my RO/DI right to my sump and was told that the constant call for water, but in very small amounts creates some kind of membrane creep, which means the membrane is used up sooner than it should be.

You're thinking of "tds creep" - the phenomenon of high tds water being produced by your water purification system when it is first turned on. If you constantly have it cycling on/off, as is the case for RO systems hooked directly to a float valve in a sump, all you may ever add to the sump are short bursts of relatively high tds water.

Russ @ BFS
 
When I found out about TDS creep that's when I decided to start asking questions about what others do. And that's one of the reasons I'm going to to strore my rodi water in a trash can and then run it to the sump. This will also do a couple of other things for me. I can avoid a disaster if my float valve fails, thus continually pumping fresh water into my tank. It will also allow me to add limewater/kalkwasser to my reservoir instead of doing it manually every day.

Scholl - I don't use a pump, it's gravity fed.

My tds went to 15 without my noticing it. I only investigated when I had a huge brown hair algae outbreak. I checked everything and then found out that color changing DI cartidges are unreliable. Although my DI color changed only halfway up (I assumed it still had life left) it was actually exhausted and giving me tds of 15. Now I check with a meter and totally disregard the color changing. It's too bad because it was very convenient everytime I drove into the garage to visually check my filter, but not anymore.
 
I wouldn't say that the color change is useless - its a convenient indicator to tell you its time to start watching your tds more closely using a meter. But it's not a precise indicator of when its time to change the cartridge, that's for sure.

Russ @ BFS
 
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