Confused on amount to Dose

[SocalS14]

My dKH is 7.0 and Calcium is 400. After 6 months, I think it's time to start dosing. I am going with 2-part - mainly due to space. I am also a DIY and would like to use Randy's formulas. I have used the calculators provided by Randy - but it leaves me confused about the amounts. Are the amounts what I should mix into 1 gallon of RODI? If so, how much do I dose in mL per day?

Stated another way; how much do I use for mixing a batch vs how much I dose per day to maintain targets?

 

[Randy Holmes-Farley Verified Community Expert]

If you have gone 6 months without dosing and are at 7 dKH, the daily demand is very low.

Do you know what alkalinity you would like the tank to be at?

 

[SocalS14]

If you have gone 6 months without dosing and are at 7 dKH, the daily demand is very low.

Do you know what alkalinity you would like the tank to be at?

Not quite true - I was adding baking soda to my ATO for the last two months when only alkalinity was dropping - but now calcium is dropping. I was shooting for 8.3 dKH

My ATO is 20gallons - so I was adding the calculated amount to raise dKH - but it just never got there. I could only get it to 7.5-7.8. I felt like I was missing something using the calculators. Now I would like to begin setting up 2-part. I am fairly savvy with DIY stuff, but no one seems to really explain all the steps in one place - or at least one place I have found.

 

[Randy Holmes-Farley Verified Community Expert]

Not quite true - I was adding baking soda to my ATO for the last two months when only alkalinity was dropping - but now calcium is dropping. I was shooting for 8.3 dKH

My ATO is 20gallons - so I was adding the calculated amount to raise dKH - but it just never got there. I could only get it to 7.5-7.8. I felt like I was missing something using the calculators. Now I would like to begin setting up 2-part. I am fairly savvy with DIY stuff, but no one seems to really explain all the steps in one place - or at least one place I have found.

Ok, I’d first suggest you read my most recent article as it is unlikely only alk was dropping, despite it looking that way.

That said, no one can tell you how much to add each day because it depends entirely on how much your tank is consuming.

Do you know roughly how much alk per day the ATO was delivering?

 

[SocalS14]

Ok, I’d first suggest you read my most recent article as it is unlikely only alk was dropping, despite it looking that way.

That said, no one can tell you how much to add each day because it depends entirely on how much your tank is consuming.

Do you know roughly how much alk per day the ATO was delivering?

I don't - I usually test once a week. So, for example, this last week I saw a drop from 7.5 to 7.0 in 5 days - but I had baking soda in ATO. I put 18 grams in roughly 20 gallons of RODI.

 

[SocalS14]

So if I wanted to bring my levels up, in order to determine how much is being used per day, do I just add the amount from the calculator over a few days and then observe/test?

 

[Mr. Mojo Rising]

The reason to dose anything is to replace what is being used, we don't dose just because we think its time. You need to know the daily consumption, this means you need to test daily and keep track for a week or two, this way you know the daily consumption, this way you know how much you need to dose, if at all.

 

[Randy Holmes-Farley Verified Community Expert]

I’d stop the ATO method, and add 0.2 dKH per day for a week and see how alk responds.

 

[SocalS14]

The reason to dose anything is to replace what is being used, we don't dose just because we think its time. You need to know the daily consumption, this means you need to test daily and keep track for a week or two, this way you know the daily consumption, this way you know how much you need to dose, if at all.

Yea - for sure. I have been charting my numbers weekly, and having been adding dKH via ATO. Noticed it was still trending down. I took that to mean it may be time to move to another approach.

 

[SocalS14]

I’d stop the ATO method, and add 0.2 dKH per day for a week and see how alk responds.

Thanks, I give that a try.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks, I give that a try.

If you find the alk is rising or falling (more than random test error) after a number of days, raise or lower the daily dose.

I'd also add calcium at a proportional rate to the alk (not based on testing), and only deviate from that if it gets too high (>550 ppm).

The reason is, at that low of demand, calcium testing will not reliably detect a change for a long time, but it is likely still being consumed at about 18-20 ppm calcium for each 2.8 dKH of alk consumed.

 

[SocalS14]

So, I worked up a batch in order to add 0.2 dKH per day. I tested ALK before dosing, and sure enough - another 7 days, another 0.5 dKH consumed. So I am starting from 6.5 dKH rather than 7.0. dKH.

 

[Randy Holmes-Farley Verified Community Expert]

So, I worked up a batch in order to add 0.2 dKH per day. I tested ALK before dosing, and sure enough - another 7 days, another 0.5 dKH consumed. So I am starting from 6.5 dKH rather than 7.0. dKH.

I'd still use the current 0.2 dKH per day dose, but correcting it up to 7 dKH in one day is fine.

 

[MnFish1]

So, I worked up a batch in order to add 0.2 dKH per day. I tested ALK before dosing, and sure enough - another 7 days, another 0.5 dKH consumed. So I am starting from 6.5 dKH rather than 7.0. dKH.

Curious - are you sure your tests are accurate?

 

[SocalS14]

Curious - are you sure your tests are accurate?

Well, I'm using a Hanna checker. I suppose I could get another brand test - but I have no reason to believe the test is inaccurate.

 

[SocalS14]

OK. Finished dosing 0.2 dKH for 5 days - last dosing day was yesterday. Measured alk today and it's 6.7 (started at 6.5). So I think I need to get it up and a little less than 0.2dKH per day should be my daily dose. How much can I increase alk per day?

 

[Js.Aqua.Project]

Yes, you can increase your tanks total Alk by up to 1dKH a day safely so if you wanted to bring it back up to 7 in one dose you can.

Then after that I would keep your daily dosing steady or even decrease it as you would already be back up to 7.

 

[Randy Holmes-Farley Verified Community Expert]

I’d just go to 0.3 dKH dosed per day. End of another week you should be above 7 dKH

 

[SocalS14]

Happy to report that my dKH is back up to 8.2 and holding steady. I have a better handle on how to dose. Thank you.

One last question - it was mentioned that I should dose calcium in proportion to dKH. What does that mean?

 

[Randy Holmes-Farley Verified Community Expert]

Happy to report that my dKH is back up to 8.2 and holding steady. I have a better handle on how to dose. Thank you.

One last question - it was mentioned that I should dose calcium in proportion to dKH. What does that mean?

It means that calcium and alkalinity are most used to deposit calcium carbonate. In that context, if alk is being used, then most likely, so is calcium. The relative rate is about 18-20 ppm calcium for each 2.8 dKH of alk consumed.

My recommendation is to replace alk as needed and use a method that adds that appropriate amount of calcium. A number of different methods add them together that way:

The Many Methods for Supplementing Calcium and Alkalinity - REEFEDITION

There is no aspect of reef aquarium chemistry more important than calcium and alkalinity. Many of my previous articles have described various aspects of these systems in detail. In reading those articles, aquarists will note one pervasive theme: that maintaining appropriate levels of each are...

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