Norms for Alk Consumption?

I am concerned about the alk levels in my tank, and am interested in dosing.. Can anyone who has a heavily stocked tank (with coral) and a significant amount of SPS please tell me what the alk consumption is in their tank (daily or weekly), or how much they have to dose to keep a constant level? If you know your pH, calcium, or mag levels, that would also be helpful. I am just trying to judge what the norm is for this...

 

In my tank I never check my ph.My tank params stay constant at 12.6 dkh,465 calc, and mag at 1400.I dose 2 ml of oceans blend part 2/ hr, 2 tsp of kents turbo calc every 24 hrs and 10 ml of oceans blend mag every 24 hrs.

 

It would not be out of the ordinary for a highly stocked SPS dominated reef tank to consume as much as 2 dkh per day

mine is currently around the 0.75 dkh per day mark at present

I use Red Sea coral pro which gives me an approx 1440 mag level when mixed at 1.026
Thus I elected to maintain my mag level around that

my Calcium level is between 420 and 440 (allowing for use interpretaton on salifert test kit
My dkh - is between 8.3 and 8.6 (again minor variations possibly slight user variation)

in general due to Alkalinity/ carbonates being used to maintain PH combined with the fact corals can utilise both Magnesium and strontium in the same manner as they use calcium
it is also typical for a reef tank to only consume up to 7ppm calcium, for each 1 dkh being utilised

which is often why some people form the opinion that their Alk is dropping faster than their calcium
simply because 1 dkh is relatively easy to see on most test kits, whereas 7ppm calcium would not be as simple to notice

Steve

 

Oh wow I never realized this. I do weekly 20-25% water changes in order to keep my levels in check. However, this method of "dosing" has recently stopped being able to keep up with the dKH my tank is using. I have taken Analytical Chemistry in college, so I have a decent idea of the pH/alk/buffer chemistry that is going on in my tank. I just never put two and two together to realize why I had to replenish the alk more than the calcium.. Thanks this helps!

 

I'm at about 2dkh per day now. I know people who are at 3 or 4 dkh per day... Sort of scary to think that your tank could crash if 1 day of dosing was missed

 

Jeez that is more than I expected... I may have messed up testing because I just measured my alk to be higher now than it was at 9 last night.

Can alk fluctuate at all? And what are alk test kits (salifert) actually measuring? Are they measuring overall alkalinity? Just carbonate?

 

Any idea how magnesium fits in here? I know that magnesium may be a little more complex because it is related to both calcium and alkalinity. I would have figured this out on my own, but I am in my final semester of college and I barely even have time to sleep. It seems like the mag goes down even slower than calcium and alkalinity. Although, I have been doing 25% weekly wc's to keep up with the levels rapidly dropping, so its a little hard to tell.

I just got a dosing pump, so I am trying to get it set up and estimate the consumptions. I plan on testing daily for 4 or 5 days, and making minor alterations until the levels are constant. My tank is using around 1 dkh/day. So I will do 7 ppm calcium/day. I am just wondering about the average for magnesium.

 

Hi gabbyr189

I believe this article by the reef alchemist should prove interesting for you

Do-It-Yourself Magnesium Supplements for the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com

my own experience with a high mag level of 1440 ish, is that my Salifert test kit is not measuring any appreciable Mag drop over a weekly period
and whilst I dose to compensate for utilsation of just over 1DHK daily at present, I am typically only dosing about 20ppm Magnesium every 4 weeks or so

Steve

 

Mine consumes quite a bit...not sure how much now...but it was enough for me to go buy a calcium reactor cuz i was sick of dosing! lol Now I just dial it in by bubbles...i keep mine at around 9.5...thinking of moving it up to 11ish soon tho.

 

Thanks! I will let you know how it goes!