refractometer usage...help

[reef tank 2.0]

i purchased a refractometer with calibration fluid. on the bottle of calibration fluid, it says to calibrate the meter using 35ppt. which i did.

so i continued to measure my salt mixture and it is reading 30ppt. so i added a half a cup more salt to the mix. let it mix and heat up, 8 hours later i remeasured it. my level is still at 30ppt. how is this possible??? it should have moved somewhat or at least a noticeable amount that would say hey add more or hey, you added too much. but nothing. no change.

the meter is pretty easy/straight forward to use. i cant imagine im doing something incorrectly but hey, anything is possible

i was gonna add more salt but dont wanna over do it. so i figured id ask for your help first.

any advice?

 

[Dkuhlmann]

How many gallons did you add the half a cup to? With most salt mixes 1/2 cup per gal will give you 1.024 give or take .001.

So how many gals did you mix and how many cups did you add the first time? If you are mixing 20 gal or so as an example I don't think that 1/2 cup would do much of anything.

All you can do is add 1/2 cup at a time until you get to 1.025-1.026

But you don't have to wait 8 hours to check the sg, just wait 15 mins or so after you put in the additional salt before you check it.

 

[reef tank 2.0]

oh crap....i was expecting major movement with that dosage amount

i have 26 gallons of water i add the salt to. i had 13.5 cups which put me at 30ppt. i added another half cup which had no effect to the total 30ppt. so i should keep adding to see what happens?

how long does it need to mix before i can test again?

 

[homer1475]

I typically wait 20 to 30 minutes, or until the water is clear again, then measure again.

If your mixing 26 gallons at a time, a 1/2 cup isn't going to make a big difference. Just keep adding and measuring till you get to where you want it, which should be somewhere around 13 to 15 cups.

 

[Dkuhlmann]

Put in a half a cup at a time like I suggested then wait about 15-20 mins if you're using a PH to mix the water. It really doesn't need anymore than to be clear after adding it.

 

[reef tank 2.0]

since i was already at 14 cups of salt with no results, i added an additional cup to another batch i have. so right now im at 15cups. i will check shortly to see where im at....

 

[reef tank 2.0]

ok, knowing what i know now, i just tested the extra cup worth of salt. it has now moved to 33ppt. so it is creeping up.

so i was thinking there would be more change per little amount of salt...........

nothing like a learning experience

thanks for the help

 

[Dkuhlmann]

Always happy to help

 

[firebirdude]

You're good man. 1/2 cup to 26 gallons is nothing.

I don't even measure my salt out. Just grab the bucket and pour it in. Eyeball it. Mix and measure with refrac. If it needs more, sprinkle in a bit more. Mix and measure. Repeat. Been doing it long enough I can get darn near 1.025 with the first dump.

 

[Happyschneider]

You added 13.5 cups of salt to a body of water which gave you a ppt of 30. How many cups do you need to add to get to 35? Solve for x

X=(13.5/30)*(35-30)=2.25

Personally, I prefer to work with weight as it is more accurate with solids but I think for this purpose cups are good enough

 

[garyinco]

Agreed on the weight thing. A cheap digital scale is good for me. I add 700 grams to 5 gallons in black buckets (Kent reef salt). Works for me.