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TDS and GH seem off?

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Background info: About 4 months ago I set up a 20 gallon long, Red Crystal Shrimp tank (my first). I let the tank cycle and added the shrimp about a month and a half ago. I use RO water and remineralize with Bee Shrimp GH+ to a TDS of around 150. Bee Shrimp GH+ claims too raise the TDS and GH of 20 litters (5.2 Gallons) RO water to 200 (+/- 50) and a GH of 6 dH with each 3 gram scoop. However I can't seem to be able to match these results.

When I add 3 grams of Bee Shrimp GH+ to 5 gallons of RO water I get a GH of 5 dH, which is what I want, but my TDS meter reads a TDS of 78ppm. If I add more of the remineralizer to match a TDS of 150ppm brings the GH to 9-10 dh which is a little too high for the Shrimp.

Is it my TDS meter just way off?

If I am getting a GH of 5 which is within the ideal range for Red Crystal Shrimp should I go with that and just add the water to my tank, even though the TDS reader reads a 78ppm?

This is my TDS Meter and I use a API GH water test kit.
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yes your TDS meter may be off. It should be periodically calibrated. You TDS meter manual should have instructions for calibrating it. But note a TDS meter will detect all solids in your water including those that are not from your GH booster. Since it is very unlikely that you have exactly the same water Bee Shrimp has, Their TDS readiness may not agree with yours. So your problem might be a miscalibrated TDS meter or a difference between your water and Bee shrimps water.
 

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1 dGH = minimum of 17.86 TDS

So 5 GH would be a minimum of ~90 TDS.

Also, are you targeting TDS or μS Microseimens? If it's 200 μS, then you are really going for ~128 TDS. If this is the case, then 1 dGH would equal ~21.33 TDS.


In short, get calibration solution for your TDS meter. I use the same TDS meter and purchased the calibration solution separately.
 

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Background info: About 4 months ago I set up a 20 gallon long, Red Crystal Shrimp tank (my first). I let the tank cycle and added the shrimp about a month and a half ago. I use RO water and remineralize with Bee Shrimp GH+ to a TDS of around 150. Bee Shrimp GH+ claims too raise the TDS and GH of 20 litters (5.2 Gallons) RO water to 200 (+/- 50) and a GH of 6 dH with each 3 gram scoop. However I can't seem to be able to match these results.

When I add 3 grams of Bee Shrimp GH+ to 5 gallons of RO water I get a GH of 5 dH, which is what I want, but my TDS meter reads a TDS of 78ppm. If I add more of the remineralizer to match a TDS of 150ppm brings the GH to 9-10 dh which is a little too high for the Shrimp.

Is it my TDS meter just way off?

If I am getting a GH of 5 which is within the ideal range for Red Crystal Shrimp should I go with that and just add the water to my tank, even though the TDS reader reads a 78ppm?

This is my TDS Meter and I use a API GH water test kit.
As mentioned, part of your problem is likely that it needs to be calibrated with the 342 ppm NaCl solution. However, this is also a .5 conversion factor meter (most in the US are). This means that, although 5 dGH is ~90 ppm, your TDS meter will only ever read about 2/3 of that. Coincidentally, this subject came up earlier today. See this link, in order to convert the reading from your TDS meter to show actual ppm content: https://www.plantedtank.net/forums/11-fertilizers-water-parameters/1290497-rodi-water-accurate-ph-readings-remineralizing.html#post11196331.

Bee Shrimp GH+ claims about raising TDS are likely based upon a .7 conversion factor meter, which matches actual ppm. The conversion calculator, in the above link, will allow you to see more correctly your actual ppm. Between that and calibrating your meter, you should be able to reach your objectives.
 

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You should trust the liquid drop test over the meter reading. For reference, I use 400mg (by weight, not scoop size) / gallon to get GH6. Be sure you wait at least 15+ minutes after mixing up a batch, because there are little crumbs that take longer to dissolve.
 
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