Confused on how to best correct Alkalinity level.

[Etoimos]

I have been having an issue getting my Alk and Cal parameters dialed in over the last several months. At some point my Cal got really high (my Red Sea test kit was maxed at over 500ppm and my Alk would drop from 9.2 dKH to 6.44 dKH in 10 days. I tried dosing more Alk as I was in Zone 4 per Chemistry And The Aquarium: Solving Calcium And Alkalinity Problems. I think I was too far tot he right on that chart, so adding more Alk did not help. I've done several large (20%) water changes and I finally have these parameters close to where they should be, but they are still not quite right.

AS of this morning they are:

Cal: 450ppm
Alk: 6.72dKH

I am dosing BRS Pharma Sodium Bicarbonate and Pharma Calcium Chloride (I'm not currently dosing the Cal as I'm above my target). Since I am still in Zone 4, should I just slowing keep upping the Alk as per the article or should I start dosing both Alk and Cal in equal parts (I've read this is a 1 to 1 two part dosing system) as I have seen per research on the net ?

Since it plays a role, my current Mag reading is 1040ppm and I use BRS Pharma Magnesium Mix for 2-Part Maintenance to dose that. All other parameters are within range.

 

[MLOPEZ]

How about your magnesium level what is your reading ?


Sent from my iPhone using Tapatalk

 

[MLOPEZ]

I just now notice you magnesium level I believe the level should be between 1250 to 1350 for magnesium .


Sent from my iPhone using Tapatalk

 

[slief]

Mag and Alk go hand in hand and when your Mg is that far out of check, your alk will be also. Start by raising your Mg to around 1300 and recheck your alk. Once you have your Mg in check, you can adjust your alk accordingly IF you need to.

 

[Etoimos]

Mag and Alk go hand in hand and when your Mg is that far out of check, your alk will be also. Start by raising your Mg to around 1300 and recheck your alk. Once you have your Mg in check, you can adjust your alk accordingly IF you need to.

Thanks. I'll slowly start bringing my Mag up. Although, when this all started my Mag was at 1240ppm which is right at the low end of what it should be. IT then went up to 1440ppm and has since dropped to the 1040ppm over the course of like 2.5 months.

 

[bertoni]

That magnesium level is very low, but it might not be much of an issue. I ran tanks at 1100 ppm for years because the old IO came at that level. I'd raise it to 1275 ppm or so, but you probably just need to keep dosing baking soda for a while.

 

[dkeller_nc]

A 2.76 dKH drop in 10 days wouldn't at all be unusual if you didn't add any 2-part during that period. You don't say what your water volume is, but folks that are new to the 2-part system are sometimes surprised at just how much sodium bicarbonate/calcium chloride their tank requires to maintain the alkalinity and calcium targets.

While magnesium is necessary to maintain the HCO3- and Ca++ ions in solution in seawater, the situation is a bit more complicated than just magnesium concentration. In particular, the amount of dissolved organics in your tank water can influence abiotic precipitation of calcium carbonate because a lot of these organics will complex divalent cations like calcium and prevent their reaction with carbonates to form calcium carbonate.

By the way - you don't state this explicitly in your first post, but I'm interpreting that you're using the procedure of not dosing any 2-part and monitoring the alkalinity/calcium over a week or so to determine the tank's demand. Unless the tank is bare, I would strongly recommend not doing this. SPS corals in particular are very sensitive to unstable alkalinity, and the procedure of "don't dose anything, monitor alk for 7 days, determine alk demand per day, dose accordingly" that I've seen in multiple places is not advisable.

Instead, pick a relatively low dose (I'd advise 1mL per gallon of standard 2-part solutions to start with). Determine the tank's alkalinity level every day (preferably at the same time of day, +/- 1 hour) for 3 days while adding that amount of 2-part every day . Make a small adjustment up or down to the amount of 2-part you're adding according to the alkalinity after the 3-day period, hold the new amount of 2-part constant for another 3 days while measuring, etc...