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How To Intepret Tds

I wanted to start a discussion here about how to interperet TDS meter readings. I have one that I have calibrated, but really don't know how to interperet the results with for my Malawi tanks. Any insight into this would be a great help. Also, does Nitrate affect TDS?
 
L

Larry-T

Guest
A TDS meter is basically an Ohmeter calibrated with a built-in conversion factor. If you want to calibrate it for your own use, take some clean tap water and make it up like you would for a new Malawi tank. Put in an airstone and let it go overnight so it will stabilize. Take a TDS reading and a pH reading. This will give you your target. As fish waste (and salts) build up, TDS will increase. So you can check your tanks regularly and use your partial water changes to maintain the water in a fairly stable condition.

I use mine to keep water for my Aphanius killies around 500 ppm and to adjust the water I incubate soft-water killifish egg in below 100 ppm.

The longer you use it, the more you will become dependent on it.
 
Just so I make sure I understand this, you are saying to use my chemical testing kit to get the water just the way I want it for Malawi's, then use that number on the TDS meter as a target for future readings right?
 
L

Larry-T

Guest
There are two ways to use the TDS meter. One is to use it to create a predetermined level of solids. The other is to put in the additives at their normal level and then test the water to make sure it's what you want. Start with an empty container of water. Prepare it as you would for new Malawi cichlids. Then, when it's all set, check the TDS. That's your overall benchmark. Chemical tests really don't enter into it, except for pH. I would not trust pH test kits anyway, because they're very inaccurate. Only use a calibrated pH meter.

The other way (which should be even more helpful) is to check the TDS of the water new fish are in PRIOR to putting them in your tank. A rapid swing in TDS can damage gills, so it's a good idea to slowly match the fish to your tank before putting them in.
 
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