alkalinity problem

[james_uk]

Hi Randy. I hope you're having better luck with your water chemistry than I'm having with mine.

Here is a table of alkalinity readings and ph buffer additions since the 3rd of August. For a given day the water was tested before the buffer was added.

Alkalinity (Meq/l) , Ph Buffer Additions (in doses)

Tue 1.6 , 2

Wed 2.4 , 0

Sun 1.83-1.94 , 2

Mon 2.74 , 0

Tue 2.63-2.74 , 1

Wed 2.86-2.74 , 2

The alkalinity test kit is by Salifert. I have no reason to believe it is in-accurate, yet. The Ph Buffer I am dosing is Seachem Marine Buffer.

I calculated the relevant dose for the volume of water (172.084068 litres) to be 10.8 mg. Rock displacement was estimated to be 10%.

According to the instructions on the bottle each dose should have raised the alkalinity by approximately 1 meq/l. Looking at the table this is clearly not the case. In just over a week I have added 7 doses and it has raised the alkalinity by not much over 1 meq/l.

Each dose was weighed out exactly using digital scales (which are new and calibrated).

Please Advise

[acroconut]

It just looks like your tank is using almost exactly 1meq/l per day of alkalinity. Seven doses (of 1meq/l each) minus 6 days at 1meq/l leaves 1meq/l. Started at 1.6meq/l ended at 1.6 + 1=2.6meq/l. You show 2.8meq/l. That all looks right.

[acroconut]

I just realized that that is actually five days of data. Therefore you are using (7-1.2)/5 = 1.16meq/l day. If your pre-dose reading is below 2.5meq/l, calculate a dose that is about 1.5meq/l and dose that per day until your pre-dose reading is about 2.5meq/l. Then dose something closer to 1.2meq/l per day and fine tune that based on keeping the pre-dose reading near 2.5meq/l.

[Randy Holmes-Farley]

First, I do not recommend using Seachem Marine Buffer in reef aquaria. It is intended for fish tanks, and has to much borate for reef aquaria, IMO.

Second, you should anticipate adding calcium and alkalinity supplements to supply corals and coralline algae with building blocks for skeletons, basically forever. So one cannot add up doses and expect the concentrations to rise over time. You have to add more than the demand to get a long term rise.

Do you know the calcium level?

These articles may help:

Solving Calcium and Alkalinity Problems
http://www.advancedaquarist.com/issues/nov2002/chem.htm

How to Select a Calcium and Alkalinity Supplementation Scheme
http://www.advancedaquarist.com/issues/feb2003/chem.htm

Reef Aquarium Water Parameters (a summary general article)
http://www.reefkeeping.com/issues/2004-05/rhf/index.htm

[james_uk]

Thanks Randy,

I'll stop using the seachem. I'm due for a water change so I'll do that (and test the fresh mix) and then start dosing my balanced additive every day. If things don't improve I'll double the dose recommended on the bottle and go from there.

I tested the calcium on the first Tuesday in the table and on the following Sunday, right after I tested the alkalinity. It was 360 ppm on both occasions.

To save confusion, I also added my balanced additive now and again to try and get the calcium level up aswell. I understand that a balanced additive provides alkalinity also.

My additive is called AragaMilk. Calcium & Buffer liquid Aragonite.
Also contains Strontium, Magnesium and Barium

Isn't Aragonite what people use in calcium reactors?

[Randy Holmes-Farley]

Uh, oh. Aragamilk isn't a good choice either, IMO. :(

Here's my review of it:

Calcium Carbonate as a Supplement (Aragamight; Liquid Reactor)
http://www.advancedaquarist.com/issues/july2002/chem.htm

I'd suggest a two part additive instead.

At least dissolve the aragamilk in fresh water before adding it.

[james_uk]

:(

Oh dear. Thanks for the information anyway. I'll look into two part additives. I see b-ionic or something a lot in topics where calcium and alkalinity are concerned

[Randy Holmes-Farley]

Yes, B-ionic is a good choice. :)

[james_uk]

Just had a thought.

How well would an arragonite substrate work, if I replaced it periodically?

[Randy Holmes-Farley]

To add calcium and alkalinity? Not very useful in most cases. Any dissolution deep down inside where the pH is lower is quite slow.