What tds is acceptable for aquarium water?

[russo36]

The OP stated "RO unit" which will never have 0 TDS since RO is only 90-98% efficient. RO/DI can and should have 0 TDS and they did state they have 0 TDS from their RO/DI after a bit which is normal once TDS creep clears. Russo I think you mean calibrate their TDS meter but again from the RO only portion of the system you will never have 0 TDS, only from the final RO/DI.

Yes correct... 0 tds is only achieved after the DI stage.... Calibration I'm referring to is initial set-up... 3-1 or 4-1 ratio. If not set correctly you won't get 0 tds.

 

[AZDesertRat]

Unfortunately most RO vendors do not supply capillary tube or adjustable flow restrictors so you are stuck with what you have. Better vendors use capillary tubes the end user can trim or adjust to get the proper waste ratio. The waste ratio though really has little to do with the treated water TDS, it is more for extending the lifespan of the RO membrane by keeping it properly flushed while in use.

 

[Taskof1]

I have an 0.16 reading, and will change media at 1.0

 

[Taskof1]

so what is an acceptable tds reading for an ro system ?

I allow up to 0.99 when my TDS reaches 1.0, I change the filters. Doesn't always have to be the membrane.

 

[MnFish1]

The problem I would see with a TDS >0 but especially > 10 or whatever is that firstly you dont know what the tds is composed of (could it be a metal for example?) and secondly - over time whatever that TDS is comprised of will slowly increase in your tank if you use that water for your top off. If your TDS is mostly copper or chloramine for example (dont know why it would be) - you're going to have problems.

EDIT FOR CLARITY: I think the only acceptable TDS is zero...

 

[chipmunkofdoom2]

I allow up to 0.99 when my TDS reaches 1.0, I change the filters. Doesn't always have to be the membrane.

This is not an effective way to manage your RO/DI filters. The only thing that final TDS tells you is if your DI resin is functioning. It doesn't tell you anything else about the state of the other filters in your RO system.

Prefilters need to be replaced every 6 months on a schedule, or as soon as you see chlorine/chloramines in the RO waste water. The reason this is important is because prefilters protect your membrane. If you don't replace the prefilters often enough, your membrane can be killed prematurely by chlorine and chloramine. Membranes last a very long time if you maintain them well. From a financial standpoint, it's worth protecting the membrane.

Same story with the membrane. The membrane only needs to be replaced when your rejection rate is below 96%. To calculate this, test the TDS of your water after the membrane, but before the DI stage. Then, test your tap TDS. Divide the post-membrane reading by the tap reading. If this is more than 0.05, your membrane needs to be replaced.

The only thing you can determine by final TDS is if your DI resin is good or bad. Everything else needs to be tested for specifically.

 

[ZoWhat]

You could make your own ultra pure H2O by combining liquid hydrogen and liquid oxygen

.... but you get a chemical reaction like this:

 

[Randy Holmes-Farley]

I have an 0.16 reading, and will change media at 1.0

What are those units? Most hobby devices do not give values below 1 ppm TDS.

 

[Randy Holmes-Farley]

You could make your own ultra pure H2O by combining liquid hydrogen and liquid oxygen

.... but you get a chemical reaction like this:

I’ve done that myself in my basement when I was a kid. I won’t say how because it is dangerous, but electrolysis of water is easy and bubbles off H2 and O2 in exactly the right ratio to remake water (and heat [emoji23]).

 

[Matt1508]

Hi

Sorry to drag up an older thread by my TDS is reading 0.08 on a TDS probe (handheld) is this considered 0 still ? I’m not sure if you guys are using a decimal unit for TDS ? This is a fairly new V2pure system with DI pod installed

 

[Randy Holmes-Farley]

Hi

Sorry to drag up an older thread by my TDS is reading 0.08 on a TDS probe (handheld) is this considered 0 still ? I’m not sure if you guys are using a decimal unit for TDS ? This is a fairly new V2pure system with DI pod installed

That is not ppm TDS. No handheld probe reads 0.08 ppm TDS. Might be 8 ppm TDS?

Which probe?

 

[Matt1508]

That is not ppm TDS. No handheld probe reads 0.08 ppm TDS. Might be 8 ppm TDS?

Which probe?

Randy - thanks yes it’s only a cheap £40 probe and I think your right ! 8ppm it is.

 

[Matt1508]

Randy - thanks yes it’s only a cheap £40 probe and I think your right ! 8ppm it is.

Think I had a duff RO membrane, installed a new one and its back to 0