TDS & RO/DI

[Jbs77]

I just received my TDS meter, and hooked it up. It read my in water at 320 TDS, and my out water at 1 to 2 TDS, however I keep having a cyano bacteria outbreak in one particular spot in my aquarium. Yes, that area is low flow, and yes I'm going to try to figure out a way to get water flow to that area.

 

I'm looking for feedback from someone who uses a TDS meter, please let me know what your TDS tracks from your RO/DI unit.

 

Thanks

Jarod

[Audi0s]

Mines borderline between 1 and 0. Filters are pretty dirty though.

[PolypHead]

Mine reads zero and when it starts to read more than that I replace the pre filter if that doesnt work I replace the next filter in line untill I have reached zero again. The lfs replaces thier filters when it reads 5.

I think cyno grows with certain types of foods high in phosphates, old lighting or wrong spectrum lights, lack of flow. I did use a product a few years ago in my reef called red slime remover. I used it at a half dose and the cyno disapeared overnight and never came back.

PolypHeads 2.5

[AZDesertRat]

Dual inline TDS meters should be installed with the IN probe after the RO membrane and the OUT probe after the DI filter on a RO/DI system. If its RO only then the only choice is before and after the RO membrane.

An RO should remove 90-98% of the tap water TDS so in your case once you move the probe where it should be you should be seeing a TDS of around 6 to 12 on the IN probe or RO only. The OUT probe or RO/DI should be 0 TDS or very close to it. Never ever let your RO/DI TDS get above 2 or 3 as this indicates you are releasing the contaminants the DI resin has been trapping and doing more harm than good.

 

Prefilters and carbons have very little to absolutely no effect on TDS and it does nothing to change them when you see TDS in the final treated water. You should always change the prefilter andcarbon every 6 months regardless of uasage as their sole purpose it to protect the more expensive RO membrane which is what removes 98% of the TDS, they only remove TSS or suspended solids and chlorine. TSS does not register on a TDS meter.

When you begin to see TDS you want to check your RO only TDS to ensure it is still functioning in the 95-98% range as well as checking the final RO/DI TDS. The resin needs replacing at this point but the prefilter, carbon and membrane are probably still good if they are less than 6 months old in the case of the filters and still doing 95-98% removal in the case of the membrane.

[Jbs77]

Glad I ordered replacement cartridges at the same time.

 

thanks

Jarod

[AZDesertRat]

Make sure you disinfect the system while you have it down. You should have received directions with the unit if you bought it new.

[amnestia]

It's not always due to the ro/di water you're using. It can be from the salt, from the fish food, from the coral food, really any number of things.

 

I have my ro/di tds meters setup with the "in-meter" plugged into the output of my ro membrane and the "out-meter" plugged into the output of my di unit. This allows me to check how efficiently the ro membrane is working and what tds water it's pumping into my di unit. TDS meters should be calibrated one or twice a year just like pH meters.