What is your in tank TDS reading?

Maxx

Maxx

Well-Known Member
I'm curious about this.
I'm in the process of setting up a 58 gallon tank with about 75 gallons total voume. Using a TDS meter from www.airwaterice.com water from the tap at my house measures at 215-218 ppm. Water from the RO/Di unit measures at 014 ppm. But since I just added IO salt mix its reading at 385 ppm with a salinity of 1.025. The salt has been in the tank less than 2 hours, but I'm wanting to know if this is what you guys see?
I dbl checked the TDS meter on my RO/DI water that I topped off the tank and that checked out at 9 ppm.
Any thoughts?
Nick
 
Maxx

Maxx

Well-Known Member
Its been about 30 minutes and the TDS reading in the tank now is 285 ppm....so its getting better. I wonder if its just reading undissolved salt particles? I have the return pump on, the skimmer on, and my closed loop is running....
We'll see.
Nick
 
Maxx

Maxx

Well-Known Member
Wow....really didnt know that. feelin kinda dumb right about now.

BTW, Welcome to Reef Sanctuary!!

Thanks for the info, cause I'd never heard that, but it makes sense.
Nick
 
ReefLady

ReefLady

Well-Known Member
Staff member
Hi Webpolk... How's Fluffy?

(I used to work with Webpolk, when I got laid off I gave him my piranha, Fluffy, because I knew it'd have a good home)
 
Cougra

Cougra

Well-Known Member
Nick:

I did the same when I got my TDS meter. I ran around testing every water source I could jsut to see what the readings were. I tested tap water and freshwater tanks and when I got to my SW tank my meter got really mad at me and gave a lot of error messages before I realised that the TDS of saltwater goes way beyond what my meter can read (up to 999ppm). I'm actually surprised it gave you any reading at all!

For what it's worth, my tap water is between 160 to 200ppm and unit output is between 2 to 5ppm. Freshwater tanks are around 150ppm to 300ppm (in planted tank with added ferts)
 
Maxx

Maxx

Well-Known Member
Cool, Like I said, I never heard this before, but it makes alot of sense....just one of those things that make you go..DOH!
Nick
 
Boomer

Boomer

Reef Sanctuary's Mr. Wizard
You can read salinity with a TDS meter, the issue is it must go to at least 40,000 ppm TDS. Such meters usually give it as ppt( as in 35 ppt NSW) or in micomhos, rather than ppm. Such a meter is a few hundred dollars, such as the one I and Randy use. Most of these meters have multiple scales, form .01 ppm to 100,000 ppm. As web pointed out, RO/DI/Tap water types are useless, as they do not read high enough. You must have missed all the threads I've had on this Maxx :turntable

Here is an example of an Ok one, not to pricy

http://www.coleparmer.com/catalog/p...ls=25638&par=&cat=1&sch=190&pfx=&lstBool=true
 
U

UnresistibleBlu

New Member
Maxx said:
I'm curious about this.
...water from the tap at my house measures at 215-218 ppm. Water from the RO/Di unit measures at 014 ppm.

I dbl checked the TDS meter on my RO/DI water that I topped off the tank and that checked out at 9 ppm.
Any thoughts?
Click to expand...

Nick - If indeed you have an RO and DI (and not just an RO), then your system is in need of some maintenance. At a minimum, your DI resin needs to be replaced. I can't tell from the info you provided if your membrane is ok.

You need to measure and monitor tds readings from 3 locations:
1. Tap water (yours read 215 ppm).
2. After the RO, but before the DI (you didn't provide this)
3. After the DI (yours read 9 ppm).

No. 2 (as compared to No. 1) above will help you evaluate how your membrane is functioning.

Blue
 
Maxx

Maxx

Well-Known Member
Blue,
Thanks for the info there. Ive had this RO/DI unit up and running for awhile, but it hasnt been running for the better part of a year. Its an Air Water Ice 5 stage Typhoon RO/DI unit, (www.airwaterice.com) and it came with shut off valves. When I stopped using it, I closed the shut off valve on the line to the water container, (after filters, there is no shut off valve before the filters). So I probably do need to replace the DI resin, but I didnt have a TDS meter until recently....just didnt think of it actually.
I dont how I can check the TDS readings from the RO but before the DI in this set up. Any suggestions?
Nick
 
dwall174

dwall174

Member
UnresistibleBlu said:
I can't tell from the info you provided if your membrane is ok.
Click to expand...
His membrane is probably ok! More than likely he has the FilmTec 100GPD Membrane (TW30-1812-100) Dow’s own Web Site calls it a “High flow 100 gallon per day drinking water element”. Not a RO element! On the other hand the 75GPD & under membranes are called a Home drinking water “RO elements”. With only a 90% rejection rate & his water at 215 TDS & an output of 14 that would be a 93% rejection. Of course it looks like his DI is toasted!
 
dwall174

dwall174

Member
Maxx said:
Its an Air Water Ice 5 stage Typhoon RO/DI unit
Click to expand...

I originally got the standard 100 GPD Typhoon that came with the Tw30-1812-100 membrane. I used the RO/DI unit for about six months & still had a bad hair algae problem. I just figured that it had to be from something else? After doing a lot of testing & ruling things out I ended up back at the RO/DI water! That’s when I figured out that something was wrong?

The TDS of my city water is only 125 ppm. Which is pretty good compared to others that I have heard about! I tested my city water & it had 3.5 mg/l Phosphates & the Silicate was off the scale. After the RO Membrane (before the DI) I still got a reading of over 2 mg/l PO4! This made me start to do some checking around & that’s what lead me to find out that the 100 GPD Dow FilmTec Membrane only has a 90% rejection rate versus a true RO membrane that has a rejection rate of 98% to 99%

After a lot of haggling & several flame wars on RC with Walter from Air Water & Ice I managed to get the membrane replaced with the High rejection rate 75 GPD Membrane. My test readings after the RO with the new membrane are now 0.5 PO4! Still a little higher than I like but the DI takes care of that.

In my case I also found out that my city water is treated with Silicate & Phosphorus acid to treat our water lines for rust & corrosion, That’s the reason for me having the high PO4 readings. My DI filters would only last about 150 gallons before with the old 100 GPD membrane. Since I switched to the 75GPD high rejection membrane I now get over 400 gallons from the DI which BTW I get from "Blue" at Buckeye Field Supply
 
D

Dakota

Member
on my water out of the ro membrane itself it tests at around 6 on the tds after the di it tests 0. i would say it has to depend on many factors like how much tds the source water has , how old the membrane is things of that nature. i would say that anything under 10 is ok. not sure though as i never get mine that high
 
Boomer

Boomer

Reef Sanctuary's Mr. Wizard
Doni

My tap is only 75-80ppt TDS

Your tap is 75,000 - 80,000 ppm (75-80ppt, seawater is 35 ppt). Even the Dead Sea is not that high :D

I now typo, 75-80 ppm :D

MAXX

That is RO/DI at 0 ppm not RO. RO will never get that low. RO will be a few ppm. A good guees is +95 % of the tap TDS
 
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