Alk levels

dhoch · #1 03/07/2005, 06:26 PM

I'm having problems with my alkalinity.

When I set up my new tank (180 upgrade from a 125) after getting everything going I did water tests.

All was good (Nitrates ~2, Nitrites 0, Amonia 0, Ph 8.25-7.95 (depending on time of day), Calcium was high ~500 and Alk was ~6.7 meq).

I started doing unbalanced dosing of B-Ionic (which was my 2 part for my 125)...

I've watched the alk go up a bit as high as 7.7 was calcium has come down to where I like it 425, but in my old tank I had a 425 calcium and a ~10 alk.

I have started adding baking soda, but I'm still get extreme drops in alk. I added 4 tsps of baking soda yesterday afternoon (alk was at 7.7 before adding). Today I test in the afternoon I'm down to 7.4. Again I add more baking soda (this time in RO water... I tested the alk of this water before adding and it was off the scale...used up 1 ml of the salifert solution).

Any ideas why I might be having what seems to me to be a large daily consumption of alk?

I do not have that much in the way of calcium using corals:
1 small candy cane
1 Medium torch
1 Small Frogspawn
1 Dersa Clam

THe rest of my corals are softies (zoos, kenya tree, xenia, a couple of leathers)

What else might be causing the drop?

Dave

redawg · #2 03/07/2005, 06:52 PM

what's your ph been running like? do you dose close to any pumps? when was the last time you cleaned any pumps? what's your usual temp range?

dhoch · #3 03/07/2005, 10:03 PM

Ph is 8.25-7.95 depending on the time of day (Pinpoint)

Temps are 78-79.

I have been adding the baking soda mixture close the my return pump...I have not cleaned it yet, but the 180 has only been set up about 1 month (and the return pump was new so I doubt that's a problem yet)...

Dave

redawg · #4 03/08/2005, 07:17 AM

has your heater been running? and do you have any build up on it?

dhoch · #5 03/08/2005, 07:49 AM

My heater only runs at night... There is some but not a large amount... WHy?

Dave

ufans · #6 03/08/2005, 08:34 AM

Read this:
http://www.wetwebmedia.com/alkalinity.htm

Don't fret too much. Your water is only slightly unstable. The balanced ALK for 425ppm Ca is about 9DKH or 3.2meq/l.

Ref: http://www.reefnerds.com/ChemPlot/ChemPlot.html

Since you are just a bit below and the fact that your Ca can still increase you might just consider adding a more balanced supplement of Kalk. Your originally high Ca levels were surely the cause of the quick depletion of ALK through calcium carbonate precipitation (which is why you should look at your heater because that is where it builds up first). I suspect now that you are down to 425ppm Ca your corals will start to even things out. I don't think that it is clear the balance of Alk and Ca in a corals diet but I suspect that there are other factors in play... such as too much CO2 in the water which needs to be aerated out.

ufans · #7 03/08/2005, 09:27 AM

Read this article as well
http://www.advancedaquarist.com/issues/nov2002/chem.htm

dhoch · #8 03/08/2005, 09:31 AM

I've read the advanced aquarist article... the other two are new to me.

I can belive the aeration... I'm working on the hood today to add some fans... maybe that will help.

What you said make sense ufans....

Should I just continue unbalanced additions? (i.e. more alk supliment then calcium) or go back to balanced.

Thansk,

Dave

ufans · #9 03/08/2005, 09:37 AM

I say go back to balanced for a day or two. or only do one more unbalanced addition of sodium bicarbonate. Since your Alk is low compared to your Ca levels then as your water balances out you will probably precipiate more Ca and you don't want that to happen a lot otherwise you will be in the reverse situation.