TDS meter/level - water question (1 Viewer)

[Capt_Swank]

What is the feeling on appropriate TDS ppm from an RO/DI unit?

So... if my tap water comes out and measures 260ppm and my RO/DI gets it down to 28ppm, is this acceptable? Do I need to change my filters?

Not sure what the max TDS ppm is before NOT using it to mix up my saltwater with.

Any comments?


Thanks.

 

[Guest]

TDS

Hmmm is the unit new, if now might want to check how long since
replaced the media. I just bought mine and when I did the last mix,
I just grabbed the plastic tub and didn't clean it out. So when was
starting water flow from the unit and check it was about 36 ppm :?
So I thought maybe since I didn't clean it out from a week ago water
change, left over something in the tub caused it to spike. Well I cleaned
and it came back down to 0.

 

[jdeveaux]

I never let mine go above 1PPM past the DI portion.

Are you measuring the water in the holding tank or directly from the clean water line?

If you are measuring with a hand held in your holding tank you'll want to make sure that the tank doesn't need to be cleaned. I clean mine about every 6 months.

My TDS after the RO is only 5-10 then 0 after DI currently.

 

[Capt_Swank]

I got my 4 stage RO/DI unit from a member (used). Not sure how old the filters were and did not have a TDS meter at that time. He assured me it was still good and had plenty of life left.

This morning I bought all new filters and membrane ($80 ouch). I will install and test TDS later today.

From seeing your TDS numbers above, I am now certain I need to replace the filter/membrane.

I am still a little unclear on what is the TDS ppm that is NOT acceptable to use? 35ppm. 25ppm, 15ppm, 1ppm, ???

What is considered the line when ppm is too high?

Thanks for the help.

John

 

[crvz]

Well you'll want to test water at a couple different places when getting ready to replace the filters. The RO membrane should last 4 years or so, and they normally reject anywhere from 90-96% of the TDS. So if you take the water measurement before the water goes through the DI resin, and it's still good, then most likely you'll only need to replace the DI resin. That cleans up the rest of the TDS, and normally lasts anywhere from 9 - 18 months. The other prefilters are pretty cheap, and can be swapped out every time or every other time you swap out the DI resin.

 

[Guest]

From what I have seen, the general consensus is to replace your filters when your TDS is above 10.

 

[crvz]

From what I have seen, the general consensus is to replace your filters when your TDS is above 10.

That's a bit of a dangerous bit of advice... again, the RO membrane is rarely going to get the source TDS under 10. It's the DI resin that pulls the last bit of solids out of the water, so if you're registering values around 10 your best bet is to swap out the DI resin before spending the $50+ on a new RO membrane.

 

[Guest]

That is true crvz. I hadn't intended to imply you should begin by replacing your RO-membrane filter Capt_Swank. I think you may want to begin by replacing your sediment, carbon, and DI filters (which should run you around $30 combined). A TDS of 28 from a 260 water source implies that the RO-membrane is still functional.

Do you know the make/model of your RO/DI unit and what filters it is composed of?

 

[Buckeye Hydro]

A TDS of 28 from a 260 water source implies that the RO-membrane is still functional.

Unfortunately, like a lot of things in this hobby, the situation is not that straightforward.

You really can't make any diagnosis on the RO membrane with just the tap water tds and the DI water tds readings. Remember that DI resin should of course lower the tds of its feedwater. If yo leave the resin in too long, it will actually start dumping tds to the water and the post DI numbers will be higher than the RO numbers.

Russ

 

[Guest]

BuckEyeFieldSupply, I believe that this scenario would still be remedied by replacing the DI filter and not the RO-membrane?

 

[Capt_Swank]

I replaced ALL the filters and membrane. Now TDS reads 1ppm.

I could have done one at a time, but at least this way I know where I am starting from.

Thanks for all the help.

 

[Buckeye Hydro]

BuckEyeFieldSupply, I believe that this scenario would still be remedied by replacing the DI filter and not the RO-membrane?

At least for a short period of time. With the information that was provided we don't know the condition of the membrane. Might be OK, might not be.

 

[Capt_Swank]

Thanks to BuckEyeFieldSupply

I bought all the internals to my RO/DI unit from BuckEyeFieldSupply. They were a great help and sent my order very fast. Thanks!!

 

[CBBSteve]

Not sure what the max TDS ppm is before NOT using it to mix up my saltwater with.

Hi, Capt_Swank.
I have never seen anyone address this, kinda interesting. Everyone tries to get as low as possible, 0 TDS is the goal. I've actually used make up water with a TDS of 30 when I needed a new RO membrane and the DI resin was exhausted. But that only happened once and I didn't see any ill effects.

Good luck,
Steve

 

[The Reef Whisperer]

What scares me is that bottled water is 20ish. Pasadena tap water is 250ish. What does this mean for our bodies?

 

[cstewart79]

nothing, drinking pure RO/DI water is actually bad for you since it trips the minerals and electrolytes from you. what you outta be afraid of is that pasadena air ...peee yeeewww..

 

[The Reef Whisperer]

what you outta be afraid of is that pasadena air ...peee yeeewww..

What do you mean "...peee yeeewww.."? Are you trying to tell me Pasadena stinks? I have noticed!

 

[AquaNerd]

pasadena, more like stinkadena

 

[The Reef Whisperer]

pasadena, more like stinkadena

Wait... Wait... Wait... (Takes deep breath) I don't smell anything!