IO calc level low or refractometer off?

[Thumbster]

Just wondering if anyone has noticed regular instant ocean salt having calcium levels around 320-340? Or is my meter off? Or does my test kit suck?

I have a ten year old bucket of IO that tests calcium at 320 and alkalinity at 7. I’m using an API test kit.

I assumed age might somehow affect the levels so I got a new bucket and retested. Calcium tests the same but alkalinity tests around 9.

I’m showing 35ppt on the refractometer prior to testing. I’m sure it needs dialed in some but I have cross checked it against a couple different lfs water and even asked them their salinity.

Just wondering if it’s me (probably) or my equipment (also probably) or the salt.

 

[EeyoreIsMySpiritAnimal]

Just wondering if anyone has noticed regular instant ocean salt having calcium levels around 320-340? Or is my meter off? Or does my test kit suck?

I have a ten year old bucket of IO that tests calcium at 320 and alkalinity at 7. I’m using an API test kit.

I assumed age might somehow affect the levels so I got a new bucket and retested. Calcium tests the same but alkalinity tests around 9.

I’m showing 35ppt on the refractometer prior to testing. I’m sure it needs dialed in some but I have cross checked it against a couple different lfs water and even asked them their salinity.

Just wondering if it’s me (probably) or my equipment (also probably) or the salt.

How did you calibrate your salinity test equipment?

 

[Sisterlimonpot]

It sounds like you're expecting homogeneous salt with every scoop containing exactly the same as the last.

Im sure age factors in, unfortunately salt mixes stratify as it ships and you're not going to get consistent readings. Your best attempt at that is going to use the entire bucket/bag of salt, because at least then you're getting what was mixed right before packaging.

 

[Thumbster]

How did you calibrate your salinity test equipment?

With a screwdriver lol.

First lfs I asked what their water was at when I bought a frag, then came home and tested the water in the frag bag with my refractometer (is there a shorter word for that?) anyway it was close to what they said.

Second lfs I bought a couple clown fish and had them test their water with a Hanna tester in front of me…then I came home and fine tuned mine using the bag water. It was very close to what their Hanna tester said.

 

[Thumbster]

It sounds like you're expecting homogeneous salt with every scoop containing exactly the same as the last.

Im sure age factors in, unfortunately salt mixes stratify as it ships and you're not going to get consistent readings. Your best attempt at that is going to use the entire bucket/bag of salt, because at least then you're getting what was mixed right before packaging.

Well I read about the settling, so prior to testing, I rolled the new bucket around, turned it upside and repeated a few times. Did that with the old bucket of salt also.

I have been making about four gallons at a time using approximately six or seven 1/2 cups each time from the old bucket and it has all tested the same. I’ve went through half or more of the old bucket.

The new bucket I’ve only made 4 gallons from. I was expecting to see much higher calcium and was surprised that it was the same even after rolling the bucket around.

 

[EeyoreIsMySpiritAnimal]

Please calibrate your refractometer with a solution of ACTUAL known salinity.

 

[Thumbster]

Please calibrate your refractometer with a solution of ACTUAL known salinity.

Well that’s where I get mentally paralyzed. I’ve almost ordered a solution off Amazon several times but then I start reading reviews. Most say it’s great, others say it’s way off.

I’ve also read through Randy’s diy salinity standard. Seems easy enough until I realize that I don’t have any 2 liter bottles and I don’t know if coke has changed bottles since that article was written.

I just ordered a gram scale off Amazon for $10 so I’ll see how that works out. If I’m understanding it correctly I add 6.2 grams of Morton salt to 161 grams of water?

 

[gbroadbridge]

Well that’s where I get mentally paralyzed. I’ve almost ordered a solution off Amazon several times but then I start reading reviews. Most say it’s great, others say it’s way off.

I’ve also read through Randy’s diy salinity standard. Seems easy enough until I realize that I don’t have any 2 liter bottles and I don’t know if coke has changed bottles since that article was written.

I just ordered a gram scale off Amazon for $10 so I’ll see how that works out. If I’m understanding it correctly I add 6.2 grams of Morton salt to 161 grams of water?

Quoting Randy:

This 3.65 weight percent sodium chloride solution can be made by dissolving 3.65 grams of sodium chloride in 96.35 grams (mL) of purified freshwater.

 

[Narideth]

I won't go into the whole ordeal I experienced with how long it took me to figure out I had an issue with my salinity, but I will sum it up with the fact that realizing my magnesium was really low eventually led to finding out that my refractometer was out of calibration by a huge factor that nearly wrecked my tank.

I tried two different calibration fluids that ended up not being correct before I purchased the TM high precision hydrometer.

While I don't want to cause alarm, it's always good to double-check your salinity if some other test is coming back with unexpected results. Just my two cents! Good luck.

 

[Thumbster]

Quoting Randy:

This 3.65 weight percent sodium chloride solution can be made by dissolving 3.65 grams of sodium chloride in 96.35 grams (mL) of purified freshwater.

Ok thanks. I was looking at the salinity standard instead of the refractive index standard. How and why those are different I have no idea lol.

 

[Thumbster]

I won't go into the whole ordeal I experienced with how long it took me to figure out I had an issue with my salinity, but I will sum it up with the fact that realizing my magnesium was really low eventually led to finding out that my refractometer was out of calibration by a huge factor that nearly wrecked my tank.

I tried two different calibration fluids that ended up not being correct before I purchased the TM high precision hydrometer.

While I don't want to cause alarm, it's always good to double-check your salinity if some other test is coming back with unexpected results. Just my two cents! Good luck.

I’m pretty sure at some point I’ve read your ordeal. I’ve spent way more time than I’d like to admit trying to get this figured out.

 

[Narideth]

I’m pretty sure at some point I’ve read your ordeal. I’ve spent way more time than I’d like to admit trying to get this figured out.

It was really frustrating and confusing at the time. I was lucky it didn't end up worse but I did lose my sapphire clowns.

I hope you get it figured out, it's definitely not a good time doubting your equipment.

 

[Thumbster]

It was really frustrating and confusing at the time. I was lucky it didn't end up worse but I did lose my sapphire clowns.

I hope you get it figured out, it's definitely not a good time doubting your equipment.

Assuming the scale is accurate I should be good from here on out. It comes with a 100g test weight and I’ll check other known weights on it.

Now I won’t have to depend on other people’s instruments or unknown solutions. Unless Randy has been lying to us all this time lol.

 

[Narideth]

Assuming the scale is accurate I should be good from here on out. It comes with a 100g test weight and I’ll check other known weights on it.

Now I won’t have to depend on other people’s instruments or unknown solutions. Unless Randy has been lying to us all this time lol.

Let us know for sure! I'm rooting for you. The scale and measured salt was suggested to me, but by the time I'd gotten to that point, I wanted an easier if more expensive solution.

 

[Thumbster]

Let us know for sure! I'm rooting for you. The scale and measured salt was suggested to me, but by the time I'd gotten to that point, I wanted an easier if more expensive solution.

I will report back with my findings!

I also contemplated the big precision hydrometer but I would break it and be mad plus I would always wonder if it was really that accurate.

I’ve never had a scale but it’s another tool for my toolbox and I can probably use it for something else in this hobby.

 

[gbroadbridge]

I will report back with my findings!

I also contemplated the big precision hydrometer but I would break it and be mad plus I would always wonder if it was really that accurate.

I’ve never had a scale but it’s another tool for my toolbox and I can probably use it for something else in this hobby.

Sooner or later you may start mixing your own additives including trace elements and an accurate scale will be worth its weight

You'll end up buying a set of volumetric flasks too.

 

[Thumbster]

Sooner or later you may start mixing your own additives including trace elements and an accurate scale will be worth its weight

You'll end up buying a set of volumetric flasks too.

Lol. I’ve already been looking at them.

 

[Randy Holmes-Farley Verified Community Expert]

I would advise that a 10 year old bucket of IO that has hardened very likely has substantial precipitation of calcium carbonate, lowering alk and calcium in the final solution once it is settled and clear.

Also, in the past the calcium level in normal IO was low by design. I'm not sure exactly when the transition took place relative to the age of this bucket. I used it specifically for that reason:

My Triton Testing Results: By Randy Holmes-Farley - REEFEDITION

Recently, Triton GmbH in Germany has initiated a method of testing many ions at once for a single price. In the US, that service is coordinated by Unique Corals. For $49 they will send you a couple of tubes to collect a tank water sample, and a prepaid mailer to send the sample back to them...

www.reefedition.com

Calcium (Ca). In my reef aquarium, I use only Instant Ocean salt and I have not added any additional calcium except as limewater for a number of years (during which time I have continued regular 1% daily water changes). So why is my calcium level (472 mg/L) higher than one would normally expect for Instant Ocean (maybe between 350 and 400 mg/L)? That long term rise in calcium is actually the expected result when using limewater to maintain alkalinity.

Limewater adds calcium and alkalinity in exactly the same proportions as in pure calcium carbonate. So if that is what is used by corals to make skeletons, and what precipitates on pumps and such, then calcium would stay constant.

But both magnesium and strontium get into growing calcium carbonate crystals in place of some of the calcium. A few percent of the calcium is replaced this way. Consequently, since the same amount of alkalinity (the carbonate) is used over time, and somewhat less than the balancing amount of calcium, calcium rises if alkalinity is maintained. I’m happy to see the result match the theory, and the calcium level seems fine to me.

 

[Thumbster]

I did have a little hardening on the top of the bucket but it wasn’t terrible. Maybe the top 1/2” or so. I broke it up and mixed it in with the rest of the salt. It was almost a full bucket.

As always, another informative article. Thank you.

I’m curious to see calcium levels after I get my refractometer dialed in. I don’t feel like I’m terribly far off.

 

[exnisstech]

Sooner or later you may start mixing your own additives including trace elements and an accurate scale will be worth its weight

You'll end up buying a set of volumetric flasks too.

I bought a portable grain scale used for reloading ammo that is pretty sweet. Can switch to grams also but measuring grains was really useful when I was experimenting with TM reef actif