Using more alkalinity than calcium?

[Annahra]

I just started dosing two part about a month ago when I noticed my alkalinity was dropping after my last round of frags went in (tank is almost five months old). I've noticed that I'm adding a lot more alkalinity than calcium. I've been doing a lot of research but can't find a good explanation that fits my tank. Should I be worried? I've attached my tracking log for the past few weeks. I do weekly 15% water changes, was using Reef Crystals but switched to Red Sea Coral Pro with my last water change. Salinity is stable at 1.025, temp runs 79-82°, and pH is 7.9-8.2 daily swing. Thanks!

 

[phillygeeks]

I had a similar experience when I was dosing two part based on Randy's formula using Sodium carbonate and Red Sea Coral Pro. At the same time I was experiencing a ton of abiotic precipitation. I did two things that I really believed help the situation. First I did was switch to using the sodium bicarbonate recipe for mixing my alk solution. Then I changed from Red Sea Coral Pro which has a fairly high baseline alkalinity to Aquaforest Reef Salt which has a much lower starting alkalinity. This seemed to break the chain of abiotic precipitation and my 2- part consumption is much much less

 

[phillygeeks]

and to your address your main issue my calcium and alkalinity consumption were similar to your same issue. They are now even to very close in daily dosing with my current salt and 2-part.

 

[McMullen]

I know of many reefers, including myself, whom dose Alk at a greater volume than Calcium.

 

[Randy Holmes-Farley Verified Community Expert]

I just started dosing two part about a month ago when I noticed my alkalinity was dropping after my last round of frags went in (tank is almost five months old). I've noticed that I'm adding a lot more alkalinity than calcium. I've been doing a lot of research but can't find a good explanation that fits my tank. Should I be worried? I've attached my tracking log for the past few weeks. I do weekly 15% water changes, was using Reef Crystals but switched to Red Sea Coral Pro with my last water change. Salinity is stable at 1.025, temp runs 79-82°, and pH is 7.9-8.2 daily swing. Thanks

Math! It is very important!!

The amount of alkalinity you are adding is very small, and you would never notice the expected calcium change. In other words, if you added the balanced calcium, calcium also would appear stable.

I'm not sure what size that tank is, but lets assume it is 50 gallons water volume.

Over 11 days you added only 23.5 mL of the alkalinity part. Assuming this is my DIY (such as from BRS), that is only 0.66 dKH over 11 days, or 0.06 dKH per day.

You would only expect to be losing 4 ppm of calcium over that entire 11 days! Your kit cannot detect that.

 

[Randy Holmes-Farley Verified Community Expert]

I know of many reefers, including myself, whom dose Alk at a greater volume than Calcium.

Almost always that comes from water changes messing with ratios. What salt mix do you use and what parameters do you maintain?

 

[McMullen]

IO reef salt
420-440
8.5-9.0

 

[Randy Holmes-Farley Verified Community Expert]

IO reef salt
420-440
8.5-9.0

Water changes with Reef Crystals and your parameters shouldn't result in more alk usage than calcium.

Abent use of tap water, the only other significant effect involves the nitrogen cycle and how nitrate is delt with. A sulfur denitrator or rising nitrate levels will deplete alkalinity and cause more alk demand than calcium.

Other than that, the effect may be very small, or an illusion of imperfect dosers, imperfect making of the two part, or testing issues.


This has more:

When Do Calcium and Alkalinity Demand Not Exactly Balance? by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2004-12/rhf/index.htm

 

[McMullen]

RODI
No reactors.

I'm merely posting a common finding. The other people that I know with similar experience all use different brand salts, no sulfur reactors, and RODI.

 

[Randy Holmes-Farley Verified Community Expert]

RODI
No reactors.

I'm merely posting a common finding. The other people that I know with similar experience all use different brand salts, no sulfur reactors, and RODI.

I don't dispute that many people think they have imbalanced demand (rightly or wrongly), but in reality, balanced dosing would work well for most people who do not have the issues I described above.

The OP is a perfect example. He asserts he has imbalanced demand/dosing and a quick read by several folks believed it. But he has no actual evidence of imbalanced demand.

IMO, the fact that alk changes way faster than calcium (on a percentage basis) when not dosing leads many people to believe they have an imbalance.

 

[Annahra]

Hi Randy,

My tank is actually a 24g with 30 lbs of rock and 40 lbs of sand, actual water volume around 15g. So it seems like I'm adding a decent amount. As per OP, I do 15% water changes weekly, had been using Reef Crystals but switched to Red Sea Coral Pro last week. Do you think it's the salt mix? Or should I be adding equal parts calcium too?

I'm using the Red Sea Reef Foundation liquids so I'm not sure how the concentrations compare. I believe 1mL of the alk is supposed to raise 25g by .1 dKH.

Thanks for your input!

P. S. * She.

 

[Randy Holmes-Farley Verified Community Expert]

I think if you added equal parts calcium, you still wouldn't see anything different, but there's no reason to not do it.

Your demand/dose is just so low (1.3 ppm per day, extrapolated from your alk demand/dose) that depletion of calcium hardly happens and water changes offset it pretty well short term.