Calibrating
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10ml cylinder for speed 0 and 50ml cylinder for speed 3. But I have changed to use kitchen scale, it is more easy to read and you can also do 5 calibrations in a row and take average, this will give a better calibration.
Member No 1
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Sounds like a good idea. Care to describe the procedure? What factor do you use? Is it variable with salinity levels?
Member No 1
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Personally I have all 3. They are good to have around not just for calibration but for the addition of additives.
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I also have a 250ml, 500ml, and 1,000ml beakers.
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I used normal tap water to do the calibration. And also used a separate set of tubing, that are just long enough to do the job.
The procedure is simple, just do 5 consecutive calibrations (or more if the dispensed amount fluctuated a lot), with the output tube dispense directly into a container placed on a tared kitchen scale. Weight the total amount of water dispensed and divided by 5. After the calibration is done and saved, I will also do a manual dosing to see if the dispensed amount is correct.
Member No 1
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Understand, thanks. However just to be clear, (I need to know the math behind it) you are using the density of RO water as the factor, and the average of the 5 test multiplied by that factor is how many ml you use as your calibration value.
Using the chart below in this example.
5 tests yields 60ml of volume. Average per test would be 12ml. Using 25*C (77F) RO water, the result would be 11.96ml. That would be your calibration value. Now I know that you can use a factor of 1 (1:1 ratio) and the resulting value would be 12ml (close enough), but there might be cases where you can't use the 1:1 ratio and this could skew the calibration value to much.
I do the same but I use the actual fluid and exactly the tubes that I going to use. In the right lengths.
Sincerely Lasse
Trivan
Community Member
From RHF DIY alkalinty test he states :
"There is a minor correction you should make when using a scale to measure the volume of seawater since 1 mL of seawater weighs a bit more than 1 gram. It will be close enough for any marine sample if you divide the weight you measure by 1.026 to get the volume. So 1,026 grams of aquarium water is 1,000 mL or 1 L. Likewise, aim for 256.5 grams for 250 mL or 513 grams for 500 mL."
"There is a minor correction you should make when using a scale to measure the volume of seawater since 1 mL of seawater weighs a bit more than 1 gram. It will be close enough for any marine sample if you divide the weight you measure by 1.026 to get the volume. So 1,026 grams of aquarium water is 1,000 mL or 1 L. Likewise, aim for 256.5 grams for 250 mL or 513 grams for 500 mL."
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