Alkalinity stability.

[Nick Barbier]

I have been struggling with keeping my 125g reef mixed tank alkalinity stable. I would like to keep the Alk between 8.2-8.5 DKH. I can get the Alk to the target parameters, but keeping it there for more than a couple of days seems to elude me. To start off with, I will dose my 2 part until I get the Alk to where I want it. Then I stop dosing for 24 hours and let the Alk drop. I measure the decrease and punch that into the Reef Chemistry calculator. The amount of 2 part that the Reef Chemistry calculator gives me, I start dosing. This should be my new daily dosing amount (correct?). However, after 2-3 days, the Alk starts to increase again. I haven't dosed any Calcium because it is staying between 450-500 ppm. If I continue to does the suggested amount of Alk from the Reef Chemistry calculator for a week, the Alk will rise from 8.2 to 9.5 DKH.
Am I doing something wrong? if so, how can I correct my mistake and keep the Alk stable?

 

[supernanoguy]

I’m also dealing with this as well. I have since decided to dose my top off water to stabilize my system which is much smaller than yours. Following for other comments.

 

[h2so4hurts]

I use a KHGuardian. Tests every 3 hours and makes adjustments to keep everything in range. You have to buy direct from their webpage (email) or their Facebook page.

drbridge|product

 

[Montiman]

While the chemistry calculator is great keep in mind that it is only as good as the assumptions you put into it.

Do you really know your tank volume? If you over estimate even a little bit you will be off.

My experience is that most people overthink dosing. If the amount you are adding is too much just drop it down a bit and test a day or two latter. If the alk goes down split the difference between what you are dosing now and what you know was too much. If your alk continues to climb then reduce the dose some more.

Think of the calculator as a recipe and the small adjustments like the extra salt and pepper the chef adds after tasting the food. The calculator gets you close but you need some adjustments because every tank is different.

 

[Marc2952]

Make sure that you are testing at the same hour every day, best way to keep it stable is to dose multiple times a day. I dose 1ml alk every hour and 1ml cal every half hour.

 

[homer1475]

While the chemistry calculator is great keep in mind that it is only as good as the assumptions you put into it.

Do you really know your tank volume? If you over estimate even a little bit you will be off.

My experience is that most people overthink dosing. If the amount you are adding is too much just drop it down a bit and test a day or two latter. If the alk goes down split the difference between what you are dosing now and what you know was too much. If your alk continues to climb then reduce the dose some more.

Think of the calculator as a recipe and the small adjustments like the extra salt and pepper the chef adds after tasting the food. The calculator gets you close but you need some adjustments because every tank is different.

This 100%. Couldn't have said it better myself.

 

[Randy Holmes-Farley]

You are probably overestimating the actual water volume (not tank size), but you may also be selecting the wrong product.

 

[BillFish Coral Lover]

I see the calculator as a tool to get from where I am to where I want to be in as quick a time as possible, within safe parameters. It is not a meant to be a calculation of how much your corals are using each day or few days. There are more sophisticated methods of determining the amount of alk, calcium and magnesium (and other lesser elements). Then the best way is to dose those amounts throughout the day. The actual amounts the corals use can fluctuate, so test as often as you can afford and are willing to do so and make very small adjustments over time. Save the regular reef calculators for larger adjustments when things get a little more off.

 

[Nick Barbier]

While the chemistry calculator is great keep in mind that it is only as good as the assumptions you put into it.

Do you really know your tank volume? If you over estimate even a little bit you will be off.

My experience is that most people overthink dosing. If the amount you are adding is too much just drop it down a bit and test a day or two latter. If the alk goes down split the difference between what you are dosing now and what you know was too much. If your alk continues to climb then reduce the dose some more.

Think of the calculator as a recipe and the small adjustments like the extra salt and pepper the chef adds after tasting the food. The calculator gets you close but you need some adjustments because every tank is different.

Thanks Montiman, I will try to make smaller adjustments. I think I will try half of what the calculator is suggesting.
To answer your question, I have a 30g sump/refugium.

 

[Nick Barbier]

You are probably overestimating the actual water volume (not tank size), but you may also be selecting the wrong product.

I've been selecting Ocean Blend, that's what I've always used to dose my reef tanks. My tank is a 125g tank with a 30g sump/refugium. But I only put in the size of the tank in the tank in the reef chemistry calculator. I don't count the sump volume.