Alkalinity dosing madness

[Tyler White]

I have been using a Hanna checker for my alkalinity (with a trident backing me up) and for the longest time i have been changing up my dosing almost on a daily basis to try to keep my alkalinity a stable 11.5 dkh and i even took it so far as to cut my doser off and do the "Lets find my daily consumption" trick and turns out it was about 1.34 dkh per 24 hour period which sounded about right. I then used BRS's reef calculator on their sodium bicarb to get 69 ml a day dosing requirement which i then split up into 20 hour increments (So i dont dose at the same time my trident does its testing and skew the results)
That was a little background on what is going on and here are the results
2:00 sept 25th 12.15 dkh
2:00 Sept 26th 10.81 dkh

Got a usage of 1.34 in a 24 hour period

In a system of 36 gallons (estimated) i should according to BRS's calculator need to dose 68.9 ml of Sodium bicarb

After 24 hours of letting my new dosing regimen run its course it is now at 11.59 (double checked by my hanna checker)

Now i could be screwing up my water volume but according to the calculator it would take 40 extra ml of sodium bicarb to get me from 10.81 (where i theoretically should be) all the way to 11.59 and i know i cannot be THAT far off with my water volume estimation as that would mean i would be off by something like 15 gallons roughly.

Now i know it sounds like a lot of crazyness but i really want to get alk as stable as humanly possible and there are alot of factors to consider since a reef environment is an ever constant changing beast of a thing and there alot of variables to consider.
My main thing is if any of you all have encountered this issue and what steps you took to counter it.
Last thing i want to have to do is get a DOS and let it work with the trident and forget all about it but knowing people have thriving stable tanks without all of that added help i want to get this done as easily as possible.

Thanks for reading and look forward to seeing what your comments are

 

[BeejReef]

I Feel your pain!

I think you're further along in the hobby than I, but no harm in trying to help.

My thoughts/questions

1) How many days did you let the tank sit without being dosed to determine your daily demand?
Two or three days is better than one

2) Are you testing and adjusting daily?
As fancy as our testers seem, they're just not always incredibly accurate. One day, it's a rock and I can test three times and get the same result 3x in a row. A week later, it's all over the place.

I'd consider sticking with your chosen best guess dose for at least two or three days and then adjust and stick for three more. Somewhere in there, you'll find balance. The corals use less alk at lower dkh and consume more at higher, so there's a natural tendency to find equilibrium.

I've seen a number of posts where people struggle to maintain significantly higher than average alkalinity, even when they did not find it hard to hold 8 or 9dkh. Dunno why.

 

[Chris L]

I am wondering why you want to try to hold your DKH to 11.5. Seems awfully high and on the razors edge of possible disaster. I'm a middle of the road type of guy myself. I'm not trying to change your thinking just wondering why.

There is an ionic balance between Calcium and Alkalinity. I think if they are too far off from each other things may go sideways. I'm no R-H-F though lol.

 

[Tyler White]

I am wondering why you want to try to hold your DKH to 11.5. Seems awfully high and on the razors edge of possible disaster. I'm a middle of the road type of guy myself. I'm not trying to change your thinking just wondering why.

There is an ionic balance between Calcium and Alkalinity. I think if they are too far off from each other things may go sideways. I'm no R-H-F though lol.

Im running an sps dominant tank and have been using coral pro salt which mixes up to about 11.5 for me on average so im trying to keep it around there.

Seeing the work brs has done on elevated levels and growth and at a higher ph droce me to choose that salt and luckily (with no skimmer) i maintain 8.3-8.5 ph every day.

 

[Randy Holmes-Farley Verified Community Expert]

I’m not really sure what you consider the problem to be, but determining the daily drop is only a rough guide to the amount needed. Much better is trial and error dosing using the drop as a starting point.

One reason is that it takes more every day to maintain 12 dKH than to maintain 10 dKH. Also, what you dose will impact pH which impacts demand. So if you need 1 dKH of sodium bicarbonate to maintain 11 dKH, you may need more than 1 dKH of sodium carbonate.

 

[Tyler White]

The main problem which in my rambling i forgot to mention is that even before when i would get my numbers relatively stable (over a few day period) i would notice a slight trend upwards and back off 2-4 ml and then get a giant drop the next day. This might be the corals getting used to the new level of stability and take off but im not quite sure and this might just be a pitfall of starting out 2 part dosing and i need to work the kinks out.

I know its not a fully set it and forget it system (is anything really in this hobby besides maybe LED's) but i feel like im going mad scientist mode trying to get my dkh where i want it to be.

And im actually in that window of relative stability right now with my screenshot that has my manual testing and trident testing overlaid. (The giant drop is me calibrating from a new shipment of reagent that came in) I am going to keep a close eye on my dkh in the coming days and see what happens and if i have to move it down i will attempt to do so with 1ml moves and water changes (since it mixes up at 11.5 roughly for me anyway.)

 

[Tyler White]

This is more of what i mean. Kept consistent at 11.5-11.68 for days and now almost 12.