[dave14]

Hi Guys,
need some help, my Kh is dropping about .5dkh per day if I don't buffer it whilst Ca is remaining stable at about 440
dkh out of reactor is 35 and i run it 15 hours a day with it being off mostly through the night.
Is it possible to increase the dkh output from the reactor without increasing the Ca

I remember some bits from Si G's summer talk but i missed alot as i was burning the sausages on the barbi lol

[karnivor]

dave14, on Oct 21 2009, 08:15 PM, said:

Hi Guys,
need some help, my Kh is dropping about .5dkh per day if I don't buffer it whilst Ca is remaining stable at about 440
dkh out of reactor is 35 and i run it 15 hours a day with it being off mostly through the night.
Is it possible to increase the dkh output from the reactor without increasing the Ca

I remember some bits from Si G's summer talk but i missed alot as i was burning the sausages on the barbi lol

Ive found that as you lower PH by either increasing CO2 or slowing flow, you tend to increase Alk production more than CA.
Using this idea, ive managed to balance my CA and Alk production to match my tank's needs.

[chriss]

Yep, second what Tony says. I was in a similar position and pondered the same issue back in the summer, but I dropped the ph by 0.05 and that did it for me. Someone did post the reasoning for it, but I can't remember it now.

Chris

[chriss]

Found it...

Quote

Chris - I think you seeing what Randy Holmes-Farley described as a mirage.

As you point out, reactor output is balanced but so should be your consumption - coral skeletons consist of 1 part calcium to 1 part carbonates. So why the apparently disporportionate fall in alkalinity?

The alkalinity (carbonate hardness) appears more volatile than calcium because alkalinity is starting from a significantly lower base. Hopefully the following will illustrate what I mean...

If calcium is 400 and carbonate is 80 then the creation of 40 units of calcium carbonate would reduce calcium levels to 360 and carbonate levels to 40. One is a fall of 10%, the other 50%! So what seems like a small drop in calcium can be reflected in a large drop in dKH.

So the converse applies - if you crank up the reactor you should see significantly bigger increases in alkalinty (carbonates) than calcium. So I suspect you won't have to go to 500ppm calcium to get your alkalinity up!

There may still be an imbalance between your calcium and alkalinty levels but I don't think its anything like as large as you think in reality.

HTH

Keith

Chris

[dave14]

Thanks,
will give it a go