My last Alk/Calcium question

[GobyMan]

Ok, yesterday morning I added 5 ml of B-ionic (each component) and then in the afternoon I tested my levels.

 

The were approx:

 

Alk 10.2 dKH/3.66 meq/l

Calcium 395

 

 

This afternoon I measured again before dosing the tank and came up with

 

Alk 9.3 dKH/3.31 meq/l

Calcium 375

 

Does that seem right? That much variation in a 24 hour period? I realize we are talking about a very small volume of water but I didn't think it would swing that much. I am now worrying about when I go on vacation for a long weekend...will my alk/calc levels plumment and cause trouble in my tank?

 

Thanks everyone for your past and future advice and help!!

[tyoberg]

Looking at your livestock, I'd say the tank is working perfectly! Pretty impressive, isn't it? My tank drops about 0.5meq/l a day, some folks lose up to 1.0 meq/l due to various calcification processes. You notice it's tracking right along as it should--it takes 0.5 meq/l for every 10ppm calcium.

 

The closer the numbers are to normal sea water, the easier it is for your corals to use them, so when your levels are lower, the rate of calcification will be lower. This will buy you more time. It's also the reason why some people have problems getting their levels up--they don't take into account that as their levels get better, it takes more dose to simply maintain the status quo.

 

As long as you stick with equal amouts of B-Ionic, you'll see your levels run up and down that 0.5meq/l for 10ppm line--you can take advantage of that and skip the calcium testing and just use your alk level to keep track of things and to determine adjustments to the daily dose.

 

Ty

[GobyMan]

Wait, dKH or meq/l?

 

If is did it meq/l it would be 3.66-3.31 or .35

and the drop in Calcium was 20 ppm.....

 

shouldn't the meq/l have fallen from 3.66 to 2.66 for your calculation to work. The more I read and think I've learned, the more I am getting confused

[tyoberg]

If you focus too hard on the numbers and decimals, you'll miss the important thing--the trend. Calcium test kits are a bit fuzzier than most people would believe--when you get a result, remember that it really has a +/- attached to it. If the number is within say 20ppm of what I anticipate it to be, it's all good.

 

If you measure every day and plot the calcium and alk levels on graph paper for a week or so, you'll see a lot of confusing ups and downs--those are due to measurement inaccuracies. The actual calcium concentration in the tank is somewhere between all those points--fit a line down the middle of the points, and you'll be very close.

 

I rely more on the alk results--the test is simpler and more reliable. So, you dropped ~1 dKH. I would expect a calcium drop of about 10ppm (with the test kits we have, it's not quite precision work here) which puts the expected calcium at 385 ppm. Yours dropped to 375ppm, putting it within 10ppm of the estimate--that's pretty good (remember, the early measurement could have been high and the later one might be low, so the error could be as much as say 40ppm).

 

Ty

[Dave ESPI]

If the Alk is up around 11-13 dkh (which is converted mg/l) then the Calcium will remain stable. Sometimes U will need to add some more calcium... For such purpose, try a bio available calcium like Seachem Reef Calcium. It is a Polyglutinate calcium, so it is great fer softies and it will provide a simple sugar energy for Active transport in the coralites. Once you get more time under yer belt, (keep a written log) you will know what ratios will work out to your benefit.