Poll: Alkalinity - Daily Demand

LuizW13 · Dec 28, 2017

How long should you monitor daily consumption levels to get a good understanding of how much is consumed on a daily basis? Before holiday break a did a series of 1 gallon or so on my system (17g) to bring the Alk up to 8 with the intention to use that as my starting point to measure the daily consumption. When i checked my water before going away, my parameteres were Alk: 8dkh, Ca: 300something, Mg: 1100something (if i remember correctly, i have to double check on my notebook).

I know that Ca and Mg is low, but why? If i brought up my Alk to 8 from 7.2 during the course of a week or so, how come the other parameters are so low? I'm using TropicMarin pro Reef salt, Hannah and Red Sea test kits.

I only have 7 small SPS frags, and no coraline algae.

Could there be something taking up the Ca and Mg?

Randy Holmes-Farley · Dec 28, 2017

LuizW13 said:
How long should you monitor daily consumption levels to get a good understanding of how much is consumed on a daily basis? Before holiday break a did a series of 1 gallon or so on my system (17g) to bring the Alk up to 8 with the intention to use that as my starting point to measure the daily consumption. When i checked my water before going away, my parameteres were Alk: 8dkh, Ca: 300something, Mg: 1100something (if i remember correctly, i have to double check on my notebook).

I know that Ca and Mg is low, but why? If i brought up my Alk to 8 from 7.2 during the course of a week or so, how come the other parameters are so low? I'm using TropicMarin pro Reef salt, Hannah and Red Sea test kits.

I only have 7 small SPS frags, and no coraline algae.

Could there be something taking up the Ca and Mg?

There's no mechanism to take up calcium and magnesium without taking up a lot of alkalinity. Check the kits in some new salt water.

Leaellynasaura · Dec 28, 2017

135 g tank with another 8og or so in sump and sand bed - I add 60ml baking soda solution daily to maintain 10.5 dKH

Israel1974 · Dec 29, 2017

daily demand is between .7 and .9 a day. I dose 70ml of BRS Sodium Bicarbonate to keep it at about 10.3 , system is 120 gallon of water, SPS that's been running since July 2017

rkpetersen · Jan 2, 2018

My mixed reef DT, with 100 circulating gallons and about 50 stony corals that are visible growing, uses 50 ml of Reef Fusion 2 per day (and I sometimes have to supplement this a bit to hold a steady target dKH of 9). According to the bottle, each ml of RF2 contains 4.4 mEq alkalinity, so I'm consuming 4.4 x 50 = 220 mEq/day in total = 0.579 mEq/l/day = 1.62 dKH/day. That actually seems about right!

CherBear811 · Mar 31, 2018

13.5 gallon fluval evo, 9 gallons system volume, with about 40 sps frags. I go through 1.7 dkh per day.

Sarah24! · Mar 31, 2018

Hello all,

Now with out me sitting down and doing the math (which I am too brain fried atm) but I test it weekly. In order for me to stay between 8.5 and 10, I have to dose my tank with alk, every Tuesday, Thursday, and Saturday. I then test usually on Sundays. If I miss a day my alk, will drop to a low 7 or 6 quickly.

At the same time I check everything else but I generally run my calcium at 440-500 in which it varies. I have noticed that my calcium drops slower than my alk, constantly. So I would need to figure out my daily measurements. But I generally use to teaspoons per two gallons of rodi.

Randy Holmes-Farley · Mar 31, 2018

Sarah24! said:
I have noticed that my calcium drops slower than my alk, constantly. So I would need to figure out my daily measurements. But I generally use to teaspoons per two gallons of rodi.

If you mean on a percentage basis, that is always the case. The expected decline ratio (barring unusual processes, such as a sulfur denitrator or substantial nitrate dosing) is about 2.8 dKH for each 18-20 ppm calcium.

ZaneTer · Mar 31, 2018

Would you maybe prefer to setup a doser to take the hassle out of having to remember to dose? It will also provide chemicals in a much more steady manner instead of spikes. You can even set the doser up to dose many times per day.

VR28man · Aug 14, 2018

Reviving an old thread..... I'm starting to watch Alk consistently because a new set of SPS are doing well.

Based on a few weeks worth of preliminary measurements (in a sometimes unstable tank) I honestly think my consumption (when things are stable!) is around 0.1dkh/day or less. And that brings me to the dilemma............

..... that is way below what can be reliably measured in one day with test kits*.

So it seems to me, rather than calculating over a few days measurement (say, 5 days leads to 0.5dkh loss which could be masked by the test kit margin of error), I should
- measure over a much longer time (say, 7-10 days which should show a notable alk loss),
- use this data to guess consumption,
- overdose by a (known and consistent) bit for a few days to get it to a target (say, 8dkh),
- once I'm at that target , and continue to dose and measure daily until I have decently high confidence that my alk is stable (accounting for the 0.3ish dkh error)
- test maybe weekly to be sure I'm on target

[29gal/110L; 1 Favites, 10 acros, 2 montis, 2 pocillopora and 1 stylophora- all added in the past month and mostly growing and showing good colors.. Going to be dosing ATI essentials once I have a good idea what my daily consumption will be. As an aside, I assume that consumption is not fixed; if these 1-2" frags all grow into decent size colonies, consumption will probably jump through the roof]

* Hanna checker has like a 0.3dkh error; reality is that sometimes my results can be different for more than that, but only sometimes. However, its basic results are on par with the ATI ICP test and my backup Salifert - the latter of which I assume also has a similar margin -, so I've used it enough to be confident in it.

Breadman03 · Aug 15, 2018

You may have a margin of error, but consistency is key. You will need to adjust your dosing as your tank matures anyway. Here is a good calculator that Randy helped out with:

http://reef.diesyst.com/chemcalc/chemcalc.html

I've been spending some time there getting my calcium reactor dialed in lately.

randyBRS · Jun 4, 2019

This is an awesome poll!

I wonder what the various 2-part additives would cost each month if they were all being used to maintain a consumption rate of 1dKH (Alk) and 7ppm (Ca)??

revhtree · Jun 5, 2019

randyBRS said:
This is an awesome poll!

I wonder what the various 2-part additives would cost each month if they were all being used to maintain a consumption rate of 1dKH (Alk) and 7ppm (Ca)??

Voted!

Jon Fishman · Jun 5, 2019

Trying to trick me into testing my water I see....... tricky.....

madweazl · Jun 5, 2019

Cant remember when I originally voted on this one but I was .1-.5 at that time but now i'm in the 1.1-1.5 range.

smartwater101 · Jun 5, 2019

I see a lot of people who dose 2-part disproportionately. If I understand correctly, excess calcium will lower alk and excess alk will lower calcium...

So... wouldn't dosing more of one just make this offset gradually worse over time? I've always thought its better to dose the same amount and just give it time to equalize. Am I missing something?

@Randy Holmes-Farley

mitch91175 · Jun 5, 2019

Mine is impossible for me to actually know the uptake with the constant addition/substration going on throughout the day. Never really not dose to see the consumption either. I'd imagine mine is pretty high running my pH peak at 8.3. If I have to guess I'd think that I am using anywhere between 2-5dKH daily. Running a calcium reactor/kalk stirrer so always adding, but my level stays around where I want it.

Right now adding 5000ml kalk daily in conjunction with the CaRx.