First time mixing salt, questions...

C

coredump

New member
Hi everyone,

My aquarium is finally ready so I started to mix my first batch of Coralife marine salt water. I ended up having to use about twice as much salt as I thought I would from reading the manufacturer's instructions to acheive 1.025 SG. Anyone have any experience with Coralife marine salt or an explanation why I required so much salt?

Here is my setup:

I have a BRS 5 Stage Chloramines PLUS RO/DI System that fills a 25 gallon container. The 25 gallon container has a heater set at 77 deg and a Maxi Jet 1200 powerhead for aeration/mixing. I have a Vee Gee STX-3 refractometer that I calibrated using PINPOINT 53.0 mS Calibration Fluid (the calibration was slightly off out of the box).


The Coralife marine salt instructions that I am using are as follows:

-----
Instructions:
Use dechlorinated tap water, distilled, deionized, or reverse osmosis water. Mix the salt in a separate container before adding to the aquarium. Add the salt to appropriate amounts of water (about ½ cup per gallon). Aerate the mixture to attain the proper gas equilibrium. Adjust the salinity (specific gravity) to the desired levels using a hydrometer. Store the remainder of the salt in a dry place.

To increase the salinity, add salt. To decrease the salinity, add water. A specific gravity of 1.021 "“ 1.023 is recommended.

Specifications:
Approximately .29lbs (about ½ cup) of Coralife Scientific grade marine salt dissolved in 1 gallon of distilled water at 78 degrees F, will yield a solution with the following properties.

Specific Gravity: 1.021-1.023
pH: 8.2-8.3
Calcium: 390-410 ppm
Magnesium: 1250-1300 ppm
-----


I ended up having to use approximately 1 cup per gallon to acheive 1.025 SG. Any ideas?

-Thanks
 
Did you add the salt slowly or all at once? While I agree it usually takes more than they state to get the desired salinity, double sounds like a bit much.
 
I added about 2 or 3 cups per hour over a period of 2 days. As I was adding it, I would take approximately a minute per cup to actually pour it into the container. So Verrrrry slowly.

Thanks for the response...
 
You can also calibrate your refractometer with RO/DI water as long as you know it's pure. Will also give you a base line of zero if you don't have a solution. But your salt seems right. You can also do by weight. I think I use 1.6 lbs per 5 gallons.
 
speedo2wet said:
You can also calibrate your refractometer with RO/DI water as long as you know it's pure. Will also give you a base line of zero if you don't have a solution. But your salt seems right. You can also do by weight. I think I use 1.6 lbs per 5 gallons.
Click to expand...

+1 If you're using a cup per gallon; it almost has to be your measuring device.
 
Salt can be added quicker than that.
I start the water into a container using a pump adding a cup every 5 gallons or so.
I have found a small container used for soup from a Chinese take out place gets you very close . When it's clear to the bottom it's ready.
 
I use Coralife salt. I mix 20g at a time and do it according to the directions too. I do have to add more to get it to 1.026, but not double the amount. I add more like an extra cup or two to get to 1.026. It is important that your water is heated and let it mix for at least a few hours before testing salinity again.

Sounds like there is some problem if it's taking double the amount.
 
Forgot to mention. Mine is mixed in the garage, I do 50 gallons at a time and have the drums plumbed to an external pump. The garage here usually sits just a few degrees higher than the house but my tanks usually sit 78-79 degrees.
 
speedo2wet said:
You can also calibrate your refractometer with RO/DI water as long as you know it's pure. Will also give you a base line of zero if you don't have a solution. But your salt seems right. You can also do by weight. I think I use 1.6 lbs per 5 gallons.
Click to expand...

I don't believe you can do that. Pure or not. I don't remember the exact explanation behind it but to properly calibrate your refractometer, you need the calibration solution of 1.026 SG. I believe the reason being is that the refractometer is not as accurate the farther out of its normal range would be, ie in the 1.001 - 1.030 range. Calibrating to zero I believe throws the accuracy off of the range you really want the most accurate, 1.023 - 1.026.

Someone correct me if I am wrong though.
 
I've read that unless you have a Milwaukee or digital refractometer, you do need a calibrating solution and can't use RODI water to be accurate.
 
When I make 4 gallons of SW in a 5 gallon bucket, I dump in 2 cups of salt, fill with 4 gallons of RO/DI, and add a powerhead. It mixes clear in about 1/2 an hour but I usually wait until the next day to add it. Not sure what the reasoning would be to add it in small amounts.
 
Kyle918 said:
I don't believe you can do that. Pure or not. I don't remember the exact explanation behind it but to properly calibrate your refractometer, you need the calibration solution of 1.026 SG. I believe the reason being is that the refractometer is not as accurate the farther out of its normal range would be, ie in the 1.001 - 1.030 range. Calibrating to zero I believe throws the accuracy off of the range you really want the most accurate, 1.023 - 1.026.

Someone correct me if I am wrong though.
Click to expand...

I'm definitely looking into it, didn't think about that. Was always just told to use a "zero" ppm distiller solution but your point and the others is valid.

As of the "cup" I always find it more accurate to use weight instead of volume when mixing salt.
 
I have always calibrated with my RO/DI water. That is what the directions state that came with my Marine and Depot refractometer. And since I know how important this is, I make sure to recalibrate every year or so. :)

I can't imagine what some people think is going to be the difference between that and calibrating with calibration solution. We are not mixing fissionable fluids together where it makes that much difference. "1.023-1.025" is what fish and corals like. I can't imagine any appreciable difference would be found with RO vs calibration solution. But I suppose if you can't sleep at night due to stuff like this, then by all means, get the calibration solution. Make sure you re-calibrate it every 4 hours depending on the phases of the moon as well.
 
You really don't want to calibrate with RO/DI. I would highly recommend that you spend a few dollars and pick up come calibration fluid. You really want to calibrate the instrument with something similar and around the same concentration as the unknown sample, especially with a 1-point calibration.
 
Just a couple of bits of advice MY OPINION ONLY
1. Always add salt to water - never the other way around due to precipitation
2. 1/2 cup per gallon will get you close
3. Put the powerhead in the RO water and sprinkle the salt in a 1/2 cup at a time. When the first is fully dissolved add the next 1/2 cup and so forth
4. Keep unused salt TIGHTLY covered. It will suck any and every bit of moisture out of the ambient air. Once is gets caked, it will not disovle.
5. Because salt is so hydrophyllic, weight should probably be more accurate than volume when measuring. This is the same reason that professional bakers weigh flour rather than dry measure.
 
Spyderturbo007 said:
You really don't want to calibrate with RO/DI. I would highly recommend that you spend a few dollars and pick up come calibration fluid
Click to expand...

When I first got my refractometer, the LFS that had the calibration fluid was closed so I DID calibrate it with RODI water to 1.026 and began using it. A few weeks afterwards I was in the store and decided to go ahead and get it then went home to calibrate. When I spread the fluid drops on the prism head (to see how far off I was) it read exactly 1.026 (EXACTLY the same as the RODI water was calibrated to).

I'm not saying the calibration fluid is worthless but I suspect it helps calibrate better with the less expensive refractometers and not so helpful with those made to more precise standards (ie usually more $$).
 
If you think about it, the prism measures the amount of salt in the water due to bending of light. If water has no salt content: RODI or a known substance that's close to nothing but H2o molecules then it technically should read zero on the scale. Also some people run their tanks a little hypo salinity for reasons. The only thing that worries me is huge swings that cause problems just like temp swings.
 
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