Alkalinity Levels Of Salt Water

[tidepool]

Okay... I have been in this hobby for 7-8 years now and have never really thought about the alkalinity of the "freshly made" salt water that I use for water changes » I just "assumed" that Instant Ocean salt crystals would give me salt water with parameters approximating that in the sea.... never really had any issues when I was in the Beavercreek area (other than the water was REALLY hard and I went through RO/DI membranes like crazy).... anyway, moved back to Canada a while back and have noticed Alk spikes when I have done water changes the last few months - just tested the Alk of the salt water I mixed 3-4 days ago and it was at 13.66 using a Hanna tester??  What's the best way to lower the Alk in the salt water before I do a water change so that the system is not exposed to a "spike" in Alk when I do a water change?

Never had this problem that I noticed before - is it the salt batch?  Water here?  I believe that I have read that one should run an air stone in your RO/DI water - but I thought that had to do with raising the pH of the water since RO/DI water tends to be on the acidic side (below 7) while our tanks run on the basic side (in the low 8's)....

Any feedback would be appreciated....

[Wall_Tank]

Good question......tagging along,  along the same manner.  I have a batch of salt that is measuring Alk:5.5dKH and Cal:320

I have dripped almost a full liter of alk (BRS soda ash mix) into my 160gal mixing tank.....and the Alk did not go up.  I'm assuming something precipitated out, but that is why I dripped it overnight.

[tidepool]

Thanks... hopefully I (we) will get some feedback from members smarter/more knowledgeable than us - I felt kinda silly asking the group this, but since you have been doing this longer than I - I feel a little better LOL! 

My RO/DI water is pristine - so it has to be the salt mix - right??

Regarding the Alk problem - I had the same issue earlier in the summer - it was because the Ca & pH levels in the tank were off so I had calcium carbonate precipitating out and on equipment - lost a few pumps because of it » so I suggest checking there 1st.... of course, this all happened when I was away on vacation for 10 days and had the nephews looking after my system - will have LFS watch now for extended vacations since they offer this service.... I have also posed the Alk question to them and will share if I hear anything worth sharing....

[mtamorrow]

following along......

[Humphrey]

http://www.advancedaquarist.com/2002/11/chemistry
Good article above... perhaps much is obvious, and I'm no expert, but some random thoughts...

Low Mag prevents uptake of Ca/Alk (I had 800 mag once )... if it's not low Mag, and both are low, one must increase both concurrently to get both to increase.  If either is proportionately low/high, one can add the missing element until balance is achieved.   I assume you’d have to add an ounce at a time alternatively to keep the levels moving up in a balanced way?

13.6 does seem a little high...  My regular IO has been mixing up at 11 or so (seems higher than it used to). 

I think IO/Reef Crystals has stepped it up so people can use water changes as the only method of supplementation.

If the Calcium is balanced (4x Alk), don't dose/Kalkwasser/Ca reactor the days you do a water change (4x Ca to Alk, so if alk is 11, Ca 440).  For example, if your new water is 13 and your current is 9, and you use .4 DKH/day, change 10% of the water will raise you DKH by the .4 you would have dosed.  If Alk is high and Ca isn't, add the water and step up the Ca as it's consumed.  1.4 DKH is the max/day advisable in the Bulk Reef Supply calculators.  They are great tools for dosing calculations.

http://www.bulkreefsupply.com/reef-calculator

[tidepool]

Thanks for the input... Mg level is fine.... I use the BRS calculators ALL THE TIME - couldn't do this hobby with out them.... doing smaller water changes more often and cutting down Alk dosing as appropriate... will be interested to see what my "next" box of IO salt crystals tests out with respect to the Alk level...

[CoralBeauties]

The last two water changes that I have done has been probably close to a 90% change.  My replacement water was very high in alk, too high to use.  I did some reading and found online to use muratic acid to lower the alk levels.  I ended up adding 20ml of acid to my 50 gallon mix drum.  It brought down my levels to about 7.7.  You do need to add and air stone to bubble out the co2 that is created from the acid reaction. It sounded pretty radical but when I read Randy holmes farley was good with it I decided to try it.
Jeff

[Humphrey]

Good to know Jeff thanks! 

[Humphrey]

One question. How do you know when you've got the co2 out?  Ph goes back up to a respectable level? 

[CoralBeauties]

I just bubbled the water overnight.  I didnt check the ph but I would guess that you could tell by the ph level.
Jeff

[AJ]

I had the same issue with the new water mixing up high. I ended up just mixing it to 1.024 and it seemed to have solved the issue. It now mixes up to 9.5 dkh when in the past (1.025) it was more like 12 dkh.

[tidepool]

Thanks for all the input guys.... I'll try mixing to only 1.024 and may even pick up a little muratic acid and use with an air stone  if necessary - same acid I used to "clean" the dry reef rock that I got from BRS, so all should be good....