alkalinity & kalkwasser

[bbyatv]

Randy,

I have read all of your articles on Calcium, Alkalinity, and pH. I have found them very helpful.

My problem is this.

I have my pH at about 8.2, my Alk at 3.5 and my Calc at 430. This is all good as far as I can tell but this requires alot of monitoring and dosing of baking soda and kalkwasser.

My 30g tank evaporates about 1 liter of water a day. I have tried all sorts of ratios of kalkwasser to try and get a stable set of parameters with know luck. If I run 2 table spoons of kalk mix in a 2 liter bottle, my alk stays good, but my calc readings go through the roof.

For some reason my tank seems to deplete alkalinity faster than calcium.

If I run 1/8 teaspoon of kalk per 2 liter bottle, my calc stays at 430 but my alkalinty drops off from 3.5 quickly.

So I have resorted to adding 1/2 teaspoon of baking soda every other day to keep the alkalinity at 3.5

I thought that using kalkwasser would keep my alk and calc in proper balance.

I have the following questions:

1. Why does my alk drop off so quickly while my calc and pH stay fairly flat?

2. Can I add baking soda to my kalkwasser solution (added using a dosing pump) or do I need to add it to the tank seperately?

3. If I stopped using kalkwasser and just added baking soda and Kent liquid calcium, could I mix the baking soda and liquid calcium in a 2 liter bottle and dose it using a dosing pump?

Any help on this problem is so appreciated.

Thanks in advance for any suggestions.

Bruce

[kngfisher]

am in the same boat.....have been told to change salt but am sceptic...I use SeaChem Reef Salt and water change about 15 to 20 gal once a month.....been using two Little Fishies Kalkwasser in my reactor for all top-off and 4 tablespoons every 3 - 4 weeks. I also add SeaChem Reef Builder .... about 3 tablespoons once a week.

My tank is a mixed SPS/LPS 90gal tank 100+ lbs of live rock....coraline growth very good by alk sitting at 6.4 dKH and calcium at 490....PH 8.3

Hope together we can figure this out.

test kits all Salifert

[Malifluous]

I have a 40 gallon, Im in The same boat as well. Ive read all of Randy's articles...........If I use limewater to replace all my evaporation my calcium goes thru the roof and alk drops. pH is fine during the day but will go below 8 at night. I use NSW and hach test kits. I have found the best way to avoid this in my tank is to do water changes but it does not really solve the problem a few days after the water change water starts to evaporate and i start dosing kalk and mess it all up. Perhaps the solution is to hold off on the kalk and just use freshwater evry other time..Im currently building a large Automatic top off and im hoping this will help stabalize everything. I really dont trust float switches cos of some horror stories Ive heard but Im tired of preparing top off water. I have recently been adding baking soda but very sparingly (like 1 tspn per week) .. Hopefully someone with concrete knowledge of what to do will chime in.

[redFishblue]

Originally posted by bbyatv

For some reason my tank seems to deplete alkalinity faster than calcium.

That is pretty normal as alk drops much quicker than calcium in a normal tank.

[Randy Holmes-Farley]

I have tried all sorts of ratios of kalkwasser to try and get a stable set of parameters with know luck. If I run 2 table spoons of kalk mix in a 2 liter bottle, my alk stays good, but my calc readings go through the roof.

That isn't possible, assuming you are using calcium hydroxide or oxide to make the limewater. Excessive limewater must result in excessive alkalinity long before you reach excessive calcium (from it alone).

What salt mix? Water changes? Using a mix like Oceanic can cause excessive calcium.

What brand lime?

Why does my alk drop off so quickly while my calc and pH stay fairly flat?

As mentioned above, that is normal. Calcium only drops by 18-20 ppm for each 1 meq/L (2.8 dKH) drop in alkalinity when calcium carbonate is formed. So alkalinity drops a lot faster on a percentage basis, while calcium levels often appear stable, within the noise of kit testing.


Can I add baking soda to my kalkwasser solution (added using a dosing pump) or do I need to add it to the tank seperately?

No, they must be separate. Also, unless you are using a salt mix with excessive calcium, you cannot do this long term as calcium will deplete. Using a two part system for extra alkalinity boost is much better, unless calcium in your water change salt mix is driving it back up continually.

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System
http://reefkeeping.com/issues/2006-02/rhf/index.php

If I stopped using kalkwasser and just added baking soda and Kent liquid calcium, could I mix the baking soda and liquid calcium in a 2 liter bottle and dose it using a dosing pump?

Nope. That is why two part systems must be two parts. Calcium carbonate will precipitate from it.

[bbyatv]

First off, I would like to thank everyone for their comments.

Randy,

Below, you said:

That isn't possible, assuming you are using calcium hydroxide or oxide to make the limewater. Excessive limewater must result in excessive alkalinity long before you reach excessive calcium (from it alone).

and

As mentioned above, that is normal. Calcium only drops by 18-20 ppm for each 1 meq/L (2.8 dKH) drop in alkalinity when calcium carbonate is formed. So alkalinity drops a lot faster on a percentage basis, while calcium levels often appear stable, within the noise of kit testing.

I am using Kent Kalk mix. I drip this in using a dosing pump. So would it be possible to drip the kalk in slow enough that the alk is droping off faster than the calc making it appear that the calc is rising and the alk is flat?

I am just trying to explain what I am seeing? I use Salifert kits and am methodical about volumes. Instead of using drips, I have measured volumes of drips and taken an average so I can use a syringe.

I do 13% water changes every 3 weeks using Instant Ocean mix. I add Kent liquid calc to the new water to bring the calcium up to 430ppm.

I am confused. If alk drops faster than calc, how can it be that you can not drip kalk at some rate where calc would rise and alk would stay level? (obviously I am not a chemist!)

I will read on the improved DIY Calc-Alk Supp system you suggested.

I now understand that I can not add my baking soda and kalk or baking soda and calc from the same bottle.

Thanks again for your time and patience.

Bruce

[Randy Holmes-Farley]

What is impossible is for calcium to rise and alkalinity to stay constant (or drop) when using limewater. Alkalinity always moves up or down faster than calcium (and in the same direction) if the only additions and subtractions are balanced additives and tank consumption.

Do you ever add the liquid calcium to the tank?

I assume that it is simply the case the the low addition of limewater is not adequate, and you need more. i suspect there was some testing or addition error when you found calcium rising on larger additions of limewater.

[bbyatv]

Thanks for the explanation. I think I get it.

If using Kalk and calc is going up, alk has to be going up faster than calc.

If using Kalk and calc is coming down, alk has to be coming down faster than calc.

Now what I have found is that when I use only baking soda to raise my alk, my calc comes down.

I only add liquid calc when doing a water change. I will add the liquid to the new water prior to the water change to raise the calc to 430 ppm.

One last question. If I am adding Kalk and my calc is stable (as close as I can measure), can my alk be coming down? I think you answered this already and the answer was yes.

Perhaps I over added liquid calc to a water change and did not know it. This would explain high calc and alk dropping I think.

Thanks again,

Bruce

[Randy Holmes-Farley]

If using Kalk and calc is going up, alk has to be going up faster than calc.

If using Kalk and calc is coming down, alk has to be coming down faster than calc.

Now what I have found is that when I use only baking soda to raise my alk, my calc comes down.

Yes, that is all normal.

One last question. If I am adding Kalk and my calc is stable (as close as I can measure), can my alk be coming down? I think you answered this already and the answer was yes.

Yes, but only because test kits are too noisy to notice a small drop in calcium. A drop of 1 dKH will only be accompanied by a 7 ppm drop in calcium.

Perhaps I over added liquid calc to a water change and did not know it. This would explain high calc and alk dropping I think.

Yes.

Use the alkalinity (and pH if it gets too high) to gauge the dose of limewater required, since it does respond to over or under dosing faster.

[bbyatv]

Randy,

Thanks so much for your advice. I appreciate you taking your time and doing this for all of us.

Bruce

[Randy Holmes-Farley]

You're very welcome.

Happy Reefing.