Are Refractometers and TDS Meters necessary?

[miktrav2]

Anyone out there using Refractometers and TDS Meters? I've got a TDS but have never used it and someone suggested that I get a Refractometer to test my salinity rather than the Hydrometer I now use as hydrometers can be off by quite a bit. Are these necessary?


Mike

 

[ErikS]

For the TDS meter...ah...um...how will you know if your RO membrane is starting to go? (w/o a TDS) An algae bloom? Poor health of livestock?

For the refractometer it depends, do you actually want to know the SG of your tank? With a hydrometer you're getting a "good guess", with a refractometer you're getting an accruate reading. Plus with w/ the refractometer you don't have to do the temp comp math :lol: Depends on the tank, for a FOWLR the SG reading of a hyrometer will be good enough.

 

[O P Ing]

hi.
Both are not necessary, but if you like buying gadgets, you will get both even if you only use one of them once in a year.

Regular cheapo floating hydrometer will work fine for most purpose, and if you replace your membrane regiously, there is no need to check the TDS reading.

 

[miktrav2]

I have an AP Tap water Purifier with color change DI resin. I change my Cartridges based on how fast the Tap Water Purifier cartridge gets exhausted.


Mike

 

[ErikS]

AP Tap water Purifier

Then as you said you have no need for a TDS meter.

As for the hydrometer, we had a "calibration" at a local club meeting. All common brands were represented. The closest ANY (out of about 20) was .03 (actual was 1.025 & it read 1.022). That's a pretty significant difference (as I said, good enough for fish maybe). The average difference was about .05 with the extreme being .08.

 

[miktrav2]

I attach the Tap Water Purifier to my 2 stage RO unit's output that's why I was asking.

Mike

 

[miktrav2]

Now I'm thinking I should dump the TDS meter and get a refractometer.


Thanks,

Mike

 

[ErikS]

I attach the Tap Water Purifier

That's the exact "system" I use, it sure extends the life of TWP cartridges. As OP Ing mentions you don't really need TDS if you change the filters & membrane on a timely basis. The TWP is designed as "one stage" unit, that is it's designed to work right off the tap. Using this you'll still never know when the RO unit needs replacement (other than just "it's time to replace"), BUT (and it's a big but) it will effectively prevent an old membrane & filters from affecting the quality of the output water (you'll just burn up cartridges faster, as if you were using it off the tap).

Another option for the refractometer is to have it calibrated on a regular basis. If you have a friend of LFS with one just compare the readings (make sure to take water temp into account). If you know the difference you can factor it into the reading. I will say a refractometer is fast & easy - a couple of drops & take a reading.