Tds help!

Hi there i just made up my r/o water for my fortnightly water change.
2 weeks ago the tds showed 001 now two weeks later it shows 029?
The water is stored in food safe buckets and the membraine, carbon block ,and sediment filters are only 3 months old!

The only thing i can think it could be that is causing the rise would be that i have never calibrated the tds meter. How often should i calibrate it??
i have cleaned it in distilled water but have no calibration fluid! (although i have just bought some on the net!)

would it be safe to use this water for this weeks change and calibrate the TDS meter before i run my next load of water?

please help.,

 

I think you can use distilled water to calibrate them too. Not 100% sure on that, but I swear I read that. Maybe some one else will chime in.

 

If that is strictly RO water and not RO/DI your readings are probably correct. Do you know what your tap water TDS is? Its not often you get a RO only TDS of 1 unless the tap water is very good to begin with.
A reading of 29 after a couple weeks is realistic when you consider RO and especially RO/DI water is very agressive and looking to attract anything it can to get back to its natural "dirty" state, as in tap water contaminant levels. It can leach things out of plastics, the air, CO2, dust etc.

To calibrate a TDS meter you need a known TDS solution such as at the bottom of the page here:
calibration solutions

 

+1 to AZ. If it's not ro/di it will not be zero.
As for the 29, is that after the storage in the buckets? If so that is normal. Even food-grade containers will leach into water.
And depending on how bad the tap is, and how much water your making, 3 months my only be the life of your canisters.

 

Put covers on the buckets. The TDS goes up because the RO/DI is absorbing contaminates from the air.

 

Something I failed to mention before is prefilters and carbon blocks have very little to absolutely nothing to do with final TDS. Thats solely the job of the RO membrane and the DI filter if you have DI. A membrane by itself is a 90-98% efficient device, its the DI that does the final polishing. There are some things a RO membrane is not good at removing such as nitrates, phosphates and silicates so DI too is a good idea in most cases.

 

Thanks for the replys guys,
so a reading of 029 could be used??

I got rid of the water i had made up and before i ran out a fresh bucket i tested a sample and it showed 001 on my tds meter?!
I guess the water i had made up previous had got contaminated??

I also tested my tap water and it showed 159?
is that good or bad??

also packleader you say buckets have a lifespan??

how often should they be changed??
as far as i was led to believe so long as its foodsafe it was ok for storing ro water??

i dont have a di filter, is this a must or is ro ok without it?
i understand it obviously helps remove more but is it vital??

My wife will kill me if i tell her i need to spend more money on "THAT BLOODY FISH TANK!!" as she calls it!! ha ha

 

159 is pretty good for tap water, the average here in the US is around 250. It really depends on what the 159 is made up of though, since TDS is not a measurement of anything specific.
I don't know that buckets have a useful lifespan but I would check them occasionally and rinse well with distilled white vinegar then a quick bleach follow up to keep them clean and bacteria free. I use the clear 5 gallon water jugs myself mostly because they are easy to cap or seal and easy to carry around and pour from.
For the few extra $$ DI is good to have.