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Discussion Starter · #1 ·
I want to set up a crystal red shrimp tank, but I ran into a problem I don't see many other people having. It is recommended that the gH should be 4-6 for CRS, while the TDS should be in the 100-160 range.

I put my salty shrimp into my gallon of distilled water until my TDS meter hits 100. When I check for gH using my test kit, its at 8, which is way too high.

My question is, should prioritize gH over TDS? Even if the TDS is at a low 40-50 but the gH is within the 4-6 range I wanted, there would be no adverse effects, right?

Thanks everyone!
 

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I legit asked the same question today on another forum as I'm having the same issue. So, curious to see the answers. one thing to note is that when you add KH it will contribute to the TDS.
 

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As @Zoidburg said, no way you can have 8 dGH and 100 ppm TDS. One degree of hardness equals about 18 ppm (17.9 if you're fussy) of TDS, hence at a minimum:

5 dGH = 5 x 18 = 90 ppm
6 dGH = 6 x 18 = 108 ppm
7 dGH = 7 x 18 = 126 ppm
8 dGH = 8 x 18 = 144 ppm

So if you remineralised to a TDS of 100 ppm, you're probably at 5 dGH. Either your TDS meter or GH test kit has to be wrong, most likely your TDS meter.

The above TDS figures are also minimum values if all the SS GH+ minerals were just GH. But they're not - there is other non-GH TDS in there too! Not a lot (e.g. compared to Seachem Equilibrium), but definitely some. From my own measurements (I've been testing a lot lately after switching to SS GH+ for both my RCS and CRS tanks):
- remineralising to 6 dGH using 1.5g per 10 litres of RO gives a TDS of about 130 ppm
- remineralising to 7 dGH using 1.75g per 10 litres of RO gives a TDS of about 150 ppm.
both of which are more than the TDS you would expect if the SS minerals were only GH. I'm pretty sure my TDS meter is accurate as it's a new HM Digital model I calibrated at 342ppm NaCl last week, but obviously there is some variation between meters.

The instructions on the pot are pretty straight forward - add 3g per 20 litres (hence my 1.5 per 10 litres) to achieve a GH of 6 degrees. From my experience and measurements this past week, this is pretty accurate. So assuming you are using the SS GH+ minerals and RO / distilled water, ditch your TDS meter, get a set of accurate mini scales and:
- add 2.0g per 20 litres to hit 4 dGH
- add 2.5g per 20 litres to hit 5 dGH
- add 3.0g per 20 litres to hit 6 dGH
- add 3.5g per 20 litres to hit 7 dGH

Or once you have a good, calibrated TDS meter, aim for 130 ppm and you should be at 6 dGH (which is what SS seem to be recommending for CRS).

Hope this helps! Regards, James =)
 

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I want to set up a crystal red shrimp tank, but I ran into a problem I don't see many other people having. It is recommended that the gH should be 4-6 for CRS, while the TDS should be in the 100-160 range.

I put my salty shrimp into my gallon of distilled water until my TDS meter hits 100. When I check for gH using my test kit, its at 8, which is way too high.

My question is, should prioritize gH over TDS? Even if the TDS is at a low 40-50 but the gH is within the 4-6 range I wanted, there would be no adverse effects, right?

Thanks everyone!
I had this same problem with this product and there is another forum thread on it that I started. I don't know how to link to it. I was told to buy a new TDS pen, recalibrate the one I had, etc. etc. I did all that; same problem. I wish I had an answer for you. I don't think you can go off of TDS with SS. I think you have to go off of GH test.
 

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One thing I always do with products like this is to turn the bottle up side down a couple of times and shake it. Learned this from 35 years of keeping saltwater aquariums. The two part chemicals separate. An will cause issues. A quick shake and all is good.
 

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One thing I always do with products like this is to turn the bottle up side down a couple of times and shake it. Learned this from 35 years of keeping saltwater aquariums. The two part chemicals separate. An will cause issues. A quick shake and all is good.
Yes... but the Salty Shrimp minerals are a powder not a liquid. Seems pretty homogeneous throughout.
 

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Out of curiosity, as Neocaridina's are often recommended an ideal tds of around 200 (150-250), the GH would have to be around 11 (11 x 18) but of course Kh would make up some of that as well as other things in the water, so how would you go about getting to roughly that TDS?
 

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Discussion Starter · #9 ·
I had this same problem with this product and there is another forum thread on it that I started. I don't know how to link to it. I was told to buy a new TDS pen, recalibrate the one I had, etc. etc. I did all that; same problem. I wish I had an answer for you. I don't think you can go off of TDS with SS. I think you have to go off of GH test.
I asked around and was told that salty shrimp is very "pure" when it comes to what they have in that powder. Because of this, there is less "extra" stuff, but has all of the essentials. Because of this, the TDS is low, but the gH is still the same. Of course, this is what I have heard from a aquarium help group, so I cannot scientifically prove this. I was conflicted with TDS vs gH because there are youtube videos that showed me how to use salty shrimp, giving me these magical TDS numbers to get a certain gH, but when I actually did it, the TDS and gH were waaaay off (aka low TDS).

With salty shrimp, I agree. Go for gH, and not TDS.
 

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TDS meter reading are not absolute so you can't compare my TDS reading with your TDS reading or anyone else's TDS reading and come to any firm conclusions. Why? Well there is actually no such thing as a TDS meter! What there are are conductivity meters which measure how much electricity flows through the water. No current flows through pure (0 TDS) water and more current flows the more impurities there are in the water. How much current depends not only on the amount of impurity but also what type of impurity it is. Electrical conductivity readings are absolute, measured in µS/cm, so if we all had EC meters (and they were all accurate) then there would be no problems, but....for some reason we all prefer to work in TDS / ppm.

We can get an idea of the TDS (ppm) by multiplying the measured electrical conductivity by a calibration factor that is about 0.5 (i.e. an EC of 200 µS/cm roughly equals a TDS of 100ppm). But this is a rough conversion, and the actual factor depends upon the impurity in the water and also on other factors such as temperature.

For aquariums, we usually calibrate our TDS meters using a NaCl (sodium chloride = salt) solution for which we know that:
700 µS/cm = 342 ppm
NaCl it seems is a reasonable approximation in terms of conductivity to the actual minerals that are in our tanks (including freshwater tanks).

So this gives us a calibration factor of 700 / 342 = 0.489. Our TDS meter is actually just a EC meter that measures the conductivity of the water, gets a reading (in µS/cm) and multiplies it by this calibration factor before displaying a readout that is in ppm (i.e. TDS).

But the actual calibration factor that a given meter uses might differ. One manufacturer might use 0.489, one 0.48, one 0.50. Or the meter could be calibrated using a different reference solution entirely ("442" is used for hydroponics applications because it better approximates nutrient solution conductivity than NaCl, where 700 µS/cm = 481 ppm, so the calibration factor is about 0.68!).

On top of this, some meters have temperature compensation whereby they tweak the calibration factor based upon the temperature of the liquid. Cheaper ones don't have temp. compensation and apply the same factor irrespective of temp, which is less accurate but you don't need a temp sensor and the meter is therefore cheaper.

In short, TDS readings are a very arbitrary number and will vary significantly from meter to meter and it is completely crazy that we use them at all! If we all stopped talking TDS and instead got EC meters which give us actual measurements, rather than actual measurements multiplied by some arbitrary factor, then our numbers would be comparable and we wouldn't all keep getting confused!

Note that the instructions on the SS minerals DO NOT MENTION TDS AT ALL for exactly this reason. They give ranges of EC that you should aim for using a EC meter.

However, TDS meters do have a use. If you use the same meter to measure your tank water you can easily see how the reading compares one day to the next, from week to week, and therefore get to understand when you need to do a water change.

You can't work out how much minerals to add to RO water using a TDS meter. But what you can do is work out how much you need to add based on the manufacturers recommendations, then upping and lowering slightly to achieve the exact desired GH and/or KH using a liquid test kit. Once you have the water the way you want it, you can then measure the TDS and use this value as a target going forward, save needing to keep doing liquid drop tests all the time. But I cannot tell you to add minerals until you get to X or Y ppm because our meters will give us potentially quite different ppm's for the same water.

If you have a TDS meter and haven't calibrated it yourself recently then the actual value will be about as accurate as dipping your finger in the water and licking it! Even a brand new meter needs calibrating, irrelevant of the "factory calibrated" claims on the box. An uncalibrated meter will let you understand how your tank water is changing day to day, but please don't be under any misunderstanding that the number is is anyway accurate or even attempt to compare with anyone else's TDS readings.

Take all TDS readings that anyone tells you or that you make yourself with an uncalibrated meter with a big big grain of NaCl!!!!!

Hope this helps clear up a little of the confusion?

Regards, James
 

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Yes... but the Salty Shrimp minerals are a powder not a liquid. Seems pretty homogeneous throughout.


The problem as with marine salt is the chemicals that make up the “mix” have particles of different sizes and will separate out. While it might seem all the same it isn’t.
 

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Discussion Starter · #12 ·
TDS meter reading are not absolute so you can't compare my TDS reading with your TDS reading or anyone else's TDS reading and come to any firm conclusions. Why? Well there is actually no such thing as a TDS meter! What there are are conductivity meters which measure how much electricity flows through the water. No water flows through pure (0 TDS water) and more current flows the more impurities there are in the water. How much current depends not only on the amount of impurity but also what type of impurity it is. Electrical conductivity readings are absolute, measured in µS/cm, so if we all had EC meters (and they were all accurate) then there would be no problems, but....for some reason we all prefer to work in TDS / ppm.

We can get an idea of the TDS (ppm) by multiplying the measured electrical conductivity by a calibration factor that is about 0.5 (i.e. an EC of 200 µS/cm roughly equals a TDS of 100ppm). But this is a rough conversion, and the actual factor depends upon the impurity in the water and also on other factors such as temperature.

For aquariums, we usually calibrate our TDS meters using a NaCl (sodium chloride = salt) solution for which we know that:
700 µS/cm = 342 ppm
NaCl it seems is a reasonable approximation in terms of conductivity to the actual minerals that are in our tanks (including freshwater tanks).

So this gives us a calibration factor of 700 / 342 = 0.489. Our TDS meter is actually just a EC meter that measures the conductivity of the water, gets a reading (in µS/cm) and multiplies it by this calibration factor before displaying a readout that is in ppm (i.e. TDS).

But the actual calibration factor that a given meter uses might differ. One manufacturer might use 0.489, one 0.48, one 0.50. Or the meter could be calibrated using a different reference solution entirely ("442" is used for hydroponics applications because it better approximates nutrient solution conductivity than NaCl, where 700 µS/cm = 481 ppm, so the calibration factor is about 0.68!).

On top of this, some meters have temperature compensation whereby they tweak the calibration factor based upon the temperature of the liquid. Cheaper ones don't have temp. compensation and apply the same factor irrespective of temp, which is less accurate but you don't need a temp sensor and the meter is therefore cheaper.

In short, TDS readings are a very arbitrary number and will vary significantly from meter to meter and it is completely crazy that we use them at all! If we all stopped talking TDS and instead got EC meters which give us actual measurements, rather than actual measurements multiplied by some arbitrary factor, then our numbers would be comparable and we wouldn't all keep getting confused!

Note that the instructions on the SS minerals DO NOT MENTION TDS AT ALL for exactly this reason. They give ranges of EC that you should aim for using a EC meter.

However, TDS meters do have a use. If you use the same meter to measure your tank water you can easily see how the reading compares one day to the next, from week to week, and therefore get to understand when you need to do a water change.

You can't work out how much minerals to add to RO water using a TDS meter. But what you can do is work out how much you need to add based on the manufacturers recommendations, then upping and lowering slightly to achieve the exact desired GH and/or KH using a liquid test kit. Once you have the water the way you want it, you can then measure the TDS and use this value as a target going forward, save needing to keep doing liquid drop tests all the time. But I cannot tell you to add minerals until you get to X or Y ppm because our meters will give us potentially quite different ppm's for the same water.

If you have a TDS meter and haven't calibrated it yourself recently then the actual value will be about as accurate as dipping your finger in the water and licking it! Even a brand new meter needs calibrating, irrelevant of the "factory calibrated" claims on the box. An uncalibrated meter will let you understand how your tank water is changing day to day, but please don't be under any misunderstanding that the number is is anyway accurate or even attempt to compare with anyone else's TDS readings.

Take all TDS readings that anyone tells you or that you make yourself with an uncalibrated meter with a big big grain of NaCl!!!!!

Hope this helps clear up a little of the confusion?

Regards, James
Oh my, thank you for putting the time to share your knowledge with us. I really appreciate the help!
 
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