Question regarding RO/DI water and TDS

Badgervet

Badgervet

Angel Fish
M.A.S.C Club Member
#1
#1
Just had something that came up that I wanted to get some opinions on.
Background info:
Normally I use a RO/DI system but its been giving me some higher TDS numbers (120-130 from the well and 15-20 after going throught the RO/DI system). It had been around 0 until this fall. I got new filters but I think its due for a new membrane and I may just get a new RO/DI unit in the near future.

The question/issue:
So while I'm getting my RO/DI issue fixed, I went to a local fish store (Greater Denver Area) and go some what I thought was RO/DI water. Got two cannisters of them and changed one of my cubes. Now i'm seen some different algae growths so I thought I'd check the TDS with my handheld (may not be the most reliable but should give me a good ball park). The TDS from the store was 120-140. (note the containers are only used for RO/DI water, not for holding any postmix salt water). I called up the store and told them about the results. The answer I got was that they run the water through 6 diffent filters and a DI (not a true RO system) and they've done that for 10 years and never had a problem. Its also why they sell the water for "cheaper" then other places.

So, whats your guys opinion? I always was taught that a zero or near zero TDS was always best.
 
Haulin Oates

Haulin Oates

Reef Shark
M.A.S.C Club Member
#2
#2
How long was it in your container? Any chance that the solids came from your container, and not the store? If not, then i would definitely stop getting water from that store. RO is what removes most of the solids in your water. DI is sort of a "polishing" agent to strip the last bit out. So if they aren't running an RO membrane, they aren't doing much except wasting DI resin.
 
J

jagermeister

Blenny
M.A.S.C Club Member
#3
#3
Water run through prefilters, an r/o, and then DI should have 0 TDS. There's something wrong with the store's filtration system or there was something in your containers.

My tap water in Arvada has 43 TDS. There's no way properly filtered water should have the TDS readings you're finding.
 
Haulin Oates

Haulin Oates

Reef Shark
M.A.S.C Club Member
#4
#4
jagermeister;205075 said:
Water run through prefilters, an r/o, and then DI should have 0 TDS. There's something wrong with the store's filtration system or there was something in your containers.

My tap water in Arvada has 43 TDS. There's no way properly filtered water should have the TDS readings you're finding.
Click to expand...
43?!? You lucky dog!! Brightons tap water regularly reads in the 300s!!!
 
Haulin Oates

Haulin Oates

Reef Shark
M.A.S.C Club Member
#5
#5
Oh and for the record I let my filters go until I get a reading of 005 on my TDS meter. I've been told I'm crazy for letting it go that high.
 
Haddonisreef

Haddonisreef

Orca
M.A.S.C Club Member
#6
#6
005 is not bad at all when your dealing w the 300's :) i fill my 180 vat twice a mth and will allow water to fill it when it reaches a tds of .010!! If he tds from lfs is high something is going on!
 
Badgervet

Badgervet

Angel Fish
M.A.S.C Club Member
#7
#7
I had a feeling that was what most people would say. The TDS from the store water was about the same or more than from my well! I guess if anyone gets water from a LFS, they should double check the TDS if possible.
And the containers that I used are only every used for RO water so I don't expect they could have gotten containated. Guess I'd better look into a new RO/DI for christmas!
 
deboy69

deboy69

Nurse Shark
M.A.S.C Club Member
#8
#8
I had the same issue. Bought my water from lfs. Did a tds and it was 60. Figured out my brown algae problem was coming from. Got my own rodi unit and it went away.
 
jahmic

jahmic

Reef Shark
M.A.S.C Club Member
#9
#9
Hate to say it...but I've bought RO water from 3 different fish stores near my house and most of them had a reading anywhere from 20-40. I think there was maybe one instance in a 2 year span where I bought RO and the TDS was under 10.

I purchased a unit for my house as well and made my life much easier. I also luck out with decent water on the Denver/Arvada border; most of the year my TDS out of the faucet is 45-65...but it's crept up to 140 now that winter is here and they've changed the water source for my area.
 
ailachami

ailachami

Tang
M.A.S.C Club Member
#11
#11
i have a tds meter and calibrated every 3-4 months. tap from aurora ranges from 150-180. king sooper is 5-15 depending on the days. i used to buy water from fish palace(lfs in aurora) and its always below 5. i run my own ro/di and i get 0-1. have you calibrated your tds meter?
 
Zooid

Zooid

Reef Shark
M.A.S.C Club Member
#12
#12
If the store ran the filtered water through a DI, then as others have said, the TDS should read zero.
If it doesn't, the store's DI resin is exhausted. On the other hand, if they are using a Kold Ster-il unit
with no DI, the TDS will not read zero, but the water is still good to use because the Kold Ster-il does
not remove calcium or alkalinity out of the tap water.
 
Badgervet

Badgervet

Angel Fish
M.A.S.C Club Member
#13
#13
ailachami;205102 said:
i have a tds meter and calibrated every 3-4 months. tap from aurora ranges from 150-180. king sooper is 5-15 depending on the days. i used to buy water from fish palace(lfs in aurora) and its always below 5. i run my own ro/di and i get 0-1. have you calibrated your tds meter?
Click to expand...
Good point, I should calibrate my TDS meter again to make sure that its reading correctly. Its one of the hand held ones and I know that they are not completely dependable. Maybe the 10-20 TDS reading I'm getting from my old RO/DI unit is actually better....could be worse also. I did compare samples that came from my ro/di unit vs. the one I got from the LFS side by side (same new containers, temperature). I figure instead of spending $80 on a new membrane, i might as well upgrade to a new/higher output ro/di unit. I've seen a lot of positive reviews on the BRS systems.
 
Cake_Boss

Cake_Boss

Blue Whale
M.A.S.C Club Member
#14
#14
Zooid;205103 said:
If the store ran the filtered water through a DI, then as others have said, the TDS should read zero.
If it doesn't, the store's DI resin is exhausted. On the other hand, if they are using a Kold Ster-il unit
with no DI, the TDS will not read zero, but the water is still good to use because the Kold Ster-il does
not remove calcium or alkalinity out of the tap water.
Click to expand...
Yessir! I loved mine.

I guess it would be a worthwhile endeavor to ask what filters they use before giving up on them.

My h2o in foco reads 41 (unit mounted tds), 0 after the ro.

After getting my own RO system I get a lot less algae.
 
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