Salt won't disolve 100%

[dennism]

This is my first SW tank.. I have a 75 gallon tank with about 50 gallons of water and reef salt in it... that's it at the moment. I added the reef salt directly to the tank from a brand new pail slowly, stirring and mixing as I went. It has been in there for about 10 days.. I have stirred up what settled out on the bottom of the tank and wiped down the inside of the tank several times, each time making the water so thick with what seems to be white salt that you can't see through it. After a couple days, some settles out, and the water clears quit a bit- 95% clear, but then I wipe down the inside and the bottom and its white again for 2-3 days.. There is less settling out each time, but is this normal? Even though it is an empty tank with nothing live in it, I have tested with all the tests in my API salt water test kit and my API reef test kit and the only item that is really high is the hardness (dKH of around 30 instead of the desired 8 to 12. I read around on forums and didn't really see anyone say a high KH was bad so... my spec gravity is only 1.019 - still just low, but I am afraid to add more salt because what is in there does not appear to be dissolving completely. I am planning on buying my live rock/sand in 5 days... I have three power heads running in the tank right now.. one brand new 400gph, and two older originally rated at 145 gph each.. (I am buying two more 400gph power heads in a couple days also). I am not running the protein skimmer yet as I only have the tank 3/4 full of water, so I have room to add sand and rock in 5 days..
Nitrate 0, nitrite 0, ammonia 0, Ca 480 mg/l dKH 30, ph 8.4. phosphate 0.. so the only rating high is dKH - is that causing a problem with the absorption of salt? What else could be wrong, or maybe nothing.. Maybe this is normal and I just don't know it??

 

[dsmlrussell]

What kind of salt are you using. I have been using reef crystals. and it does the same thing. I think a few other people have had the same problem with RC.

 

[roka64]

Do you have a heater running?
Are you using a hydrometer or refractometer?
The hydrometers don't adjust of water temp. It is best to premix your water, with a ph and heater.
Are you using tap water?
It could be the silt from your sand.
What kind of sand are you using?

Oh yeah, Welcome to the site!

 

[dennism]

I am using instant ocean reef crystals.. So will this just go away after a few more days?? Temp 81, hydro meter, tap water.
no sand yet - just water and salt.

 

[Kurt_Nelson]

I am using instant ocean reef crystals.. So will this just go away after a few more days?? Temp 81, hydro meter, tap water.
no sand yet - just water and salt.

Probably not. I remember when I first filled my tank (Reef Crystals) there was what I considered then a fair amount of white "dust" that wouldn't mix. It eventually ended up at the bottom of my sand bed! What will dissolve has dissolved, and what's left over isn't a big deal. I mix and store my saltwater in a separate heated tub now (which is a good idea!) and there's always a little in the bottom that just never dissolves.

Your alkalinity reading of 30 dkh seems waaaaay off though. Even with hard tap water, I just can't imagine it really being that high. Using an API test kit, that would mean you put in 30 drops before it changed from blue to yellow? Is this what you did? If it's truly that high, then that will be a problem... but I'm thinking that either the test kit is bad or perhaps there was "user error". Any way to get someone else to independently test that either at a LFS or a buddy?

 

[fijiwigi]

When I mix my Reef Crystals in my mixing tub I slowly add salt a scoop at a time with the powerhead running giving it time to dissolve a bit. It sits about a week or so before I put it in my tank. After a week there is some chunky salt at the bottom of the mixing tank not much but there is some that does not dissolve but not enough to be a big deal.

 

[lance]

This is just undissolved elements and should be fine. To avoid this going in the main tank then premix your batch and use a good powerhead to circulate water and let mix overnight or 12 hours. Differant salt brands will leave more behind then others.

 

[dennism]

Thanks for all the tips! I repeated the hard water test last night with the API test kit and came up with a dKH of 29 - yes 29 drops of the test fluid, one at a time, shaking in between, before it changed colors. I am not sure if I need to change that or just ignore it.. to change it, I guess I will have to go buy something to take more iron out of the water, or buy RO water or.. sigh.. Anyway, at least I know I don't have to worry about the white water issue I have.. it settled out today again to be 95% clear.. so I'll just leave it on the bottom and put my live sand on top.. thanks again for all the posts!

 

[Kurt_Nelson]

It's not iron that makes the high alkalinty... it's carbonate - most likely calcium carbonate, because with Reef Crystals a calcium reading of 480ppm is like a dream come true! (In other words, it just doesn't happen!) For comparison, Reef Crystals made up with RO/DI water to about 1.025 salinity comes up around 360 ppm Ca and around 8 dkH for alkalinity.

I'm guessing you have super hard water, huh? Live in the Midwest USA maybe?

Maybe some folks that use tap or well water with high alkalinity can give you some first hand advice, but I think 29 dkH is going to give you problems if you end up going with corals. There's a delicate balance between alk and calcium that you don't need to know right now, but here's some links for when you want to read more about it...

Calcium and Alkalinity by Randy Holmes-Farley - Reefkeeping.com
Chemistry and the Aquarium

 

[MarineFlake]

RO/DI keeps the reef doctor away....

 

[ccCapt]

IMO, 29 or 30 dKH in saltwater is impossible. All the carbonate, most likely sodium carbonate since we are talking alk, would precipitate out of the water. You would have a blizzard in your tank from the super saturation and after the precipitation settled, your alk reading would be very, very low.

I will also add that many corals start to "burn" with alk readings of 12 dKH and above.

 

[Ziggy953]

Well as for the salt not dissolving all the way that is a minor issue. No worries there....

The 29dKH however is a problem. Since you haven't put anything in the tank yet I would wait for sure! Test your tank water for dKH and see what you get. If it is off the charts then you have an issue. I would strongly recommend getting RO/DI water or buying an RO/DI unit and use it. If your water is that hard out of the tap then you would do well to not use straight tap water!

dKH in my system is 9, just tested it this morning....

 

[Kurt_Nelson]

IMO, 29 or 30 dKH in saltwater is impossible. All the carbonate, most likely sodium carbonate since we are talking alk, would precipitate out of the water. You would have a blizzard in your tank from the super saturation and after the precipitation settled, your alk reading would be very, very low.

I was thinking it was impossible also, but heck... those API tests are pretty foolproof and I don't thing anything goes "bad" in the alkalinity test, do they?

I was also wondering if the white stuff that didn't dissolve was the residue from the "snowstorm", but like you said then the alkalinity would be very low.

Is there something in the water that the alkalinity test could be "reading" as carbonate hardness? In other words... even though the test says it's 30, in reality it's more like 8 or something? I'm not a chemist so I'm not sure how those tests work.