RO/DI & TDS - Update on filter change...

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debdp

Premium Member
I purchased an RO/DI unit in about October '07 I believer. I run it probably about 2 times a week either filling RO drinking water or the DI to fill my water containers for the aquariums. I took samples from the faucet, our RO drinking water and the DI that is used for the tanks.

Faucet read: 196
RO Drinking read: 0.04
DI read: 0.04

What do I need to do to get the DI to 0? Do I need to change the filters or something? I thought you didn't have to change those for a year or something like that. Just checked and I ordered it last week of October but really didn't start using it until the 2nd week of November. So it's only been in use for 3 months.
 
What meter reads like that? .04 is .96 less than 1 TDS - pretty good.

Even if it is 4 TDS, that isn't anything to lose sleep over. However, it could be your DI resin is all used up and must be replaced.

Filters are usually good for 6 months, not 12.
 
Can you explain exactly how you tested the TDS? Did you let the unit run for at least 2 minutes before taking a sample? Was it a hand-held device or an inline device? Have you tried to test distilled water to make sure the meter can read 0?

The DI might be all used up already, especially since TDS creep is very high for the first 60 seconds.
 
Okay ran a new test. Started the unit and let it run for 2 minutes filling a small container. Then I filled a small cup from the hose and took another reading. Now it reads 9. The water I measured originally came from the holding container and not directly from the unit. Guess it's time to replace some filters. It's the meter that I purchased with the unit, HM Digital hand held.
 
If your RO water and your RO/DI water are reading the same I would suspect your DI is exhausted. Try replacing your DI cartrige (or refill it) and test again.
 
Update: I ordered replacement filters from Marc, got them like the next day (Thanks Marc!! Super service). As soon as I changed all filters (yesterday) I started running some water through to the DI. Meter read 0 :lol: So all old water has been dumped and now refilling RO/DI and remixing salt. Darn cold weather makes it run slower. Tried the hose in the water bucket thing... my heaters are too small and the water is like ice so the heaters couldn't keep up.

Anyway here's a picture of the DI. This is after about 3 months use. Now I have two 28 gallon containers for water storage. So with my nanos & brackish tank the amount of water changed out weekly is only about 16-18 gallons. The amount of top off is negligible, maybe 2-3 gallons between all tanks a week. So I'm pretty surprised that the unit needed to be replaced so soon. Is this normal? An odd occurrence? Dependent on water coming into house?

As this is my first and first time dealing with filters, I'm pretty clueless as to what they're supposed to look like. I do remember noticing that it started turning brown like within the first month and just got more and more brown. But did not know if that meant anything or not.
 
One more question: I just read where someone had copper wire exposed into tank. And someone else mentioned hey heard of brass causing problems. Does this apply to saltwater coming in contact with brass, copper fittings, pipes only? Or does it contaminate freshwater, too, as there are copper pipes in the house which the tapwater runs through and the Y I put in the washroom that connects to washing machine and RO/DI unit is a brass Y. Thanks.
 
The DI should have still be good for a while, until the resin is orange to the top. However, that is merely a visual indicator and a TDS meter reports the absolute truth.

Brass or copper used before the RO/DI system is fine. The plumbing in your walls and foundation are usually copper in most modern homes. A brass fitting after the RO/DI would be a bad place to have such a fitting because the water is so pure, it acts like a corrosive and will add metal to the water.

I replaced my DI resin 11/28/07 - and within a month it looked just like yours. I tested it yesterday, but it is working as it should. I didn't last as long as I would have expected, visually speaking.
 
Well I did good sized water changes in 4 tanks, my 3 reef and my brackish. I was even getting cyano in the brackish tank. So now the cyano is starting to go away on its own. My red macroalgae had gone into overdrive which is a good thing because I think if it had not I would have more bad algae issues. My zoas though did not appreciate the water change. I had no cyano in their tank but different macralgaes started popping up. Some of the zoas closed up for a couple days, after the water change, including the new zoas I just won at NextWave. They have not opened back up :( but the others are doing have. So another decent water change in the other three (not touching zoa tank) should get everything back under control. No wonder my chaeto was growing like crazy as well. I would've never thought the water could have that much affect.
 
I make about 50 gallons of salt water a week out of an ro/di system and have had to change the resin in quite a while. It's been going on for several months and my TDS reading is 2. I can live with that. When it gets to 4 or higher, I'll change the resin. I digitally check the TDS about every week.

Resin is pretty cheap, but I guess it depends on what type of system you have.
 
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