Measuring Salt

djplus1 · 09/08/2012, 09:00 AM

I was wondering if there was any difference in where you took salt measurements from. For instance, I just did a water change in my 72g bowfront. I added freshly mixed saltwater to the sump. After around 20 minutes, I took a measurement with my refractometer in the sump which got a reading of 36 ish and then I decided to take a measurement from the display (around an inch from the top of the tank) and that reading was 31ish.

Which number is more accurate? Neither... perhaps if it takes a while to mix together completely? Which location should I be taking my measurement from?

Dexters Reef · 09/08/2012, 09:26 AM

It shouldn't matter because eventually both will be the same. I think since you added saltwater to the sump, not all of it diluted with the main tank water causing different readings. If 20 min gave different readings, I would check again in a few hours to see if those numbers are closer

disc1 · 09/08/2012, 10:38 AM

If they are that far apart you're doing something wrong when you read it.

disc1 · 09/08/2012, 10:40 AM

Was the water you changed in at a different salinity that the water that was already in the tank? If not then it shouldn't make any difference even if it hasn't mixed through.

roninmagik1 · 09/08/2012, 10:41 AM

yah, i'd wait for a little, for all the water to mix, when i do water changes, i wait for a couple minutes, and then take my salt water readings...

dublo8 · 09/08/2012, 11:30 AM

Quote:

Originally Posted by disc1

If they are that far apart you're doing something wrong when you read it.

Agreed. Even if I just did a water change, my numbers match, no matter where I pull the sample from. Your tank water should match your fresh mixed SW to avoid swings in salinity and the health of the inhabitants. Most of the fish and invertebrates in your tank cannot handle salinity swings very well. it's not a matter of letting it "mix in". It should match from bucket to tank exactly.

djplus1 · 09/10/2012, 07:47 AM

I agree with yall who are saying that the measurements SHOULD be the same, but I was raising salinity in a new tank (5 weeks) that only has 4 hermits and two snails in it. The instant ocean mix that I have only gets me to 1.021 if I mix it EXACTLY the way they say it. To make it easier, I did a 10 gallon water change with significantly more salt to raise the salinity to 1.026 (which it is now, BTW) which is apparently why I had a higher reading in the sump (where new water was added) vs the display.

Now speaking of instant ocean, does anyone else have issues getting it to mix at 1.026 following directions (1/2 cup/Gallon). I have made SW 3 or 4 times now and always end up with around 1.020-21 at most. It seems I have to add at least 2 to 4 cups than needed to 10-15 gallon container I mix in.

disc1 · 09/10/2012, 08:17 AM

How do you calibrate that refractometer?

Lwhite · 09/10/2012, 08:27 AM

Quote:

Originally Posted by disc1

How do you calibrate that refractometer?

+1

And yes, the mixes are usually 1/2 cup/gallon for 1.021. You have to titrate salt to bring it up to where you are at. I usually mix to 1.021 for 4 gallons (in a 5 gall bucket) and then slowly add salt until I get to 1.025

09/08/2012, 09:00 AM	#1
djplus1 Registered Member Join Date: Sep 2012 Posts: 8	Measuring Salt I was wondering if there was any difference in where you took salt measurements from. For instance, I just did a water change in my 72g bowfront. I added freshly mixed saltwater to the sump. After around 20 minutes, I took a measurement with my refractometer in the sump which got a reading of 36 ish and then I decided to take a measurement from the display (around an inch from the top of the tank) and that reading was 31ish. Which number is more accurate? Neither... perhaps if it takes a while to mix together completely? Which location should I be taking my measurement from?

09/08/2012, 09:26 AM	#2
Dexters Reef Registered Member Join Date: Aug 2012 Posts: 730	It shouldn't matter because eventually both will be the same. I think since you added saltwater to the sump, not all of it diluted with the main tank water causing different readings. If 20 min gave different readings, I would check again in a few hours to see if those numbers are closer __________________ 75G RR, Trigger Systems Ruby 30S sump, 2x250 MH and 4x54W T5HO, Octopus Diablo XS160, 4" DSB, 2 x MP40wES, 85 lbs LR, 2 x BRS Dosing Pumps, Finnex 300w titanium heater, Surf2 Algae Turf Scrubber

09/08/2012, 10:38 AM	#3
disc1 -RT * ln(k) Join Date: Sep 2010 Location: Little Rock Posts: 9,705	If they are that far apart you're doing something wrong when you read it. __________________ David Current Tank: Undergoing reconstruction...

09/08/2012, 10:40 AM	#4
disc1 -RT * ln(k) Join Date: Sep 2010 Location: Little Rock Posts: 9,705	Was the water you changed in at a different salinity that the water that was already in the tank? If not then it shouldn't make any difference even if it hasn't mixed through. __________________ David Current Tank: Undergoing reconstruction...

09/10/2012, 08:17 AM	#8
disc1 -RT * ln(k) Join Date: Sep 2010 Location: Little Rock Posts: 9,705	How do you calibrate that refractometer? __________________ David Current Tank: Undergoing reconstruction...

09/08/2012, 10:41 AM	#5
roninmagik1 Registered Member Join Date: Sep 2007 Location: Pembroke Pines, FL Posts: 259	yah, i'd wait for a little, for all the water to mix, when i do water changes, i wait for a couple minutes, and then take my salt water readings...

09/10/2012, 07:47 AM	#7
djplus1 Registered Member Join Date: Sep 2012 Posts: 8	I agree with yall who are saying that the measurements SHOULD be the same, but I was raising salinity in a new tank (5 weeks) that only has 4 hermits and two snails in it. The instant ocean mix that I have only gets me to 1.021 if I mix it EXACTLY the way they say it. To make it easier, I did a 10 gallon water change with significantly more salt to raise the salinity to 1.026 (which it is now, BTW) which is apparently why I had a higher reading in the sump (where new water was added) vs the display. Now speaking of instant ocean, does anyone else have issues getting it to mix at 1.026 following directions (1/2 cup/Gallon). I have made SW 3 or 4 times now and always end up with around 1.020-21 at most. It seems I have to add at least 2 to 4 cups than needed to 10-15 gallon container I mix in.