Dosing alk question

[J Rog]

I have a question on dosing. I just started dosing my newer tank. I see a lot of people dose alk at night and CA during the day. So I dose via an Neptune Dos ML of Alk between midnight and 10:59am. When I tested my alk around 1pm today and it tested 9.4 DHK. I just tested again and it’s at 8.6 DHK. Just wanted to see if this is a normal drop range through out the day. My goal is to stay steady in the 8.5 range. For further reference I am dosing CA in equal amounts as alk.

 

[redfishbluefish]

So what you're saying is that within about an 8 hour period you alk dropped 0.8 dKh. That seems a bit high unless you're packed with hard corals/clams....but let's not worry yet. You do have test variance. I'd suggest testing again tomorrow at about the same time (1:00PM) and see if it's around 9.4. It's best to do your testing at about the same time of day.

 

[J Rog]

Yes, that’s via the Hanna alk checker. I have 3 sps frags in there. I thought I was holding steady at 8.5 ish but decided today to do a test earlier and a test later because one of my sps frags (pearl berry) starting losing some tissue at the base. It’s the only Frag showing anything negative at this point. But it has me in a testing frenzy.. I tested CA and Mag 2 days ago and all is good there. Mag was at 1470 and CA was at 460. So I’m really thinking it’s my alk. But the Pearl berry just went in the tank last Wed.

 

[reefndude]

I dose alk and calcium all day long. Alk on the hour and cal on the 1/2 hour. Test results are always within 1 or 2 ppm from last test. For example today it tested 133 ppm yesterday tested 132 ppm day before tested 133 ppm

 

[J Rog]

I dose alk and calcium all day long. Alk on the hour and cal on the 1/2 hour. Test results are always within 1 or 2 ppm from last test. For example today it tested 133 ppm yesterday tested 132 ppm day before tested 133 ppm[

I don’t think I can set up the dose by the hour with the Neptune Dos. But I can set up 2 intervals of which to dose over the course of 24 hours with the dos you have to set it up on 12 hour intervals. Do you suggest I do that?

 

[saltyhog]

I dose alk and calcium all day long. Alk on the hour and cal on the 1/2 hour. Test results are always within 1 or 2 ppm from last test. For example today it tested 133 ppm yesterday tested 132 ppm day before tested 133 ppm

That is how I dose as well.

The Hanna calcium checker uses a very small sample and is subject to some user error if you are not really careful in how you take your sample. What are you using to take your sample? If you're using a 2cc or 5cc syringe that could introduce some error. A 1cc insulin type syringe would be better.

 

[reefndude]

I dose for 17 straight hours. Alk starts at 6:30 am and doses 17 times. Cal starts at 9:30am and again 17 times throughout the day. I stopped dosing in the through the night because parameters always increased. Consumption just stopped according to my test results. I suggest dosing as many times as you can throughout the day to keep your tank as stable as possible.

 

[reefndude]

That is how I dose as well.

The Hanna calcium checker uses a very small sample and is subject to some user error if you are not really careful in how you take your sample. What are you using to take your sample? If you're using a 2cc or 5cc syringe that could introduce some error. A 1cc insulin type syringe would be better.

I just fill to the line on the testing bottle. Slight water curve above and below the line. Tried adding 10 ml of water but didn't leave much room for reagent so I just use the line.

 

[EmdeReef]

Do you have a lot of coralline, that could explain alk usage.

Even if your alkalinity moved by about 0.8 in a day it shouldn’t stress the coral to lose tissue, could be something else or just the initial adjustment. How long have you had the frag? How old is the tank?

 

[J Rog]

Do you have a lot of coralline, that could explain alk usage.

Even if your alkalinity moved by about 0.8 in a day it shouldn’t stress the coral to lose tissue, could be something else or just the initial adjustment. How long have you had the frag? How old is the tank?

Picked up the frag last Thurs. so only a couple of days. Tank is very young. 4 months. I know I know.. to young for sps. But thought I had everything stable for the most part. Plus I got a free sps frag that was bleached out. Didn’t really think it was alive when I got home with it. But 3 weeks later and it’s gained a ton of color compared to when I got it. So I figured if I could bring a frag back from death I think I should be able to keep a healthy one going.. lol

 

[Randy Holmes-Farley Verified Community Expert]

There are several different theories on the best way to dose. Some tanks seems to have most of the demand during the day, and dosing just during these hours seems to lead to the most stable alkalinity.

Some others choose to dose at night when pH is lowest to bring up the lower end of the pH range.

I'm not actually certain which is "best" and the answer may depend on things like how low the pH is otherwise getting, what creatures are in the tank, and what are the criteria for "best".

 

[J Rog]

There are several different theories on the best way to dose. Some tanks seems to have most of the demand during the day, and dosing just during these hours seems to lead to the most stable alkalinity.

Some others choose to dose at night when pH is lowest to bring up the lower end of the pH range.

I'm not actually certain which is "best" and the answer may depend on things like how low the pH is otherwise getting, what creatures are in the tank, and what are the criteria for "best".

I was hoping you might make an appearance here! Thanks! As of now with my current dosing schedule the lowest my PH gets is 8.0 and the highest is 8.3. I’m about to do an alk test so I can see if it matches up with yesterday’s reading.. then will do another one tonight and see where I’m at. But if it’s the same I may just try switching up to dosing Alk during the day and CA at night

 

[Randy Holmes-Farley Verified Community Expert]

I was hoping you might make an appearance here! Thanks! As of now with my current dosing schedule the lowest my PH gets is 8.0 and the highest is 8.3. I’m about to do an alk test so I can see if it matches up with yesterday’s reading.. then will do another one tonight and see where I’m at. But if it’s the same I may just try switching up to dosing Alk during the day and CA at night

Thet sounds like a good plan.

The new generation of automatic alk titrators that are yielding values for alkalinity 24/7 have been quite useful for determining when during the day alk is being consumed.

We still are not certain, IMO, how much alk is being consumed by organisms and how much by abiotic precipitation, the latter of which definitely would peak during the day when pH is highest.

I've tried to get someone to use some sort of offsetting pH control to have pH lower during the day than at night to see when alk demand peaks, but no takers yet.

 

[Randy Holmes-Farley Verified Community Expert]

For example, I'd like to know:

1. Assuming alk demand is highest during the day, is that because corals use more then or abiotic demand peaks then (or both)?
2. Assuming coral demand for alk is highest during the day, is that because of the pH rising during the day, or a direct effect of photosynthesis in the coral?