Alkalinity increase without dosing

pharazon

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Hello!

As a disclaimer, I have Googled and searched my issue thoroughly. I just wanted to get a second opinion.

Tank was started with cured man-made live rock. Live meaning it had a healthy population of critters - mini bristleworms, stomatella snails, sponges etc. Two or theee weeks after adding our first corals, alkalinity began to drop. We started dosing, and determined that 2.5ml of ESV 2 part kept alkalinity stable.

Alkalinity demand increased after the addition of more corals, and our dose increased to 3.5ml to keep alkalinity stable.

A few weeks ago, we spent a night away from the house and as a result that tank did not receive a dosage of 2 part for 24 hours. We checked it before continuing our normal dosage, and found that it has dropped approximately 1 dKh. Corals were happy, did not seem stressed by the drop. We continued with our previous dosing amount.

We tested alk a few days later, and found that alk had gone up despite dosing the same amount as we had previously. Perhaps demand had changed. To rule out testing error, we dosed the same amount again and tested the following day. Alk continued to rise slightly. We determined that adjusting 1.75ml maintained alk steady.

We continued this amount for several days before seeing a drop. Again, we ruled out testing error by dosing the same amount again before adjusting. We then determined 2.5ml maintained steady alk.

Dosage remained at 2.5ml for several days before testing and finding that alk had again gone UP. To see how much it would drop, we did not dose for 24 hours. Alk remained unchanged. Another 24 hours, still unchanged. Last night, day 3 of not dosing, alk had INCREASED.

About the tank:

Our rock is man made, and I understand that artificial rock has the potential to leach and raise alkalinity. This was not an issue for several months, so I’m not sure why it would start to so long after the tank was set up.

We have never had nitrates over 5ppm or phosphates over 0.1 ppm. I understand that a sudden drop could cause alkalinity to increase, but I’m under the impression it would have to be a much larger drop.

I appreciate any input and feedback you folks might have!
 

Larry L

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Are you testing alkalinity at the exact same time every day? Consumption varies.

What are you using to test it? You might be trying to chase numbers that are within the range of measurement variability (e.g. if your alk is around 8 the Hanna dKH checker can read plus/minus about 0.7 according to the specs).
 
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pharazon

pharazon

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Are you testing alkalinity at the exact same time every day? Consumption varies.

What are you using to test it? You might be trying to chase numbers that are within the range of measurement variability (e.g. if your alk is around 8 the Hanna dKH checker can read plus/minus about 0.7 according to the specs).

We use Hanna checker and the same time we’ve day.

I understand what you’re saying about chasing numbers, but I don’t think that’s not the case. Perhaps the increase since we stopped dosing is just testing variance. I am most concerned about alkalinity not decreasing after three days, even factoring in the acceptable accuracy range.
 

TX_Punisher

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Stop dosing them check over several days.

I had the same issue. Yes, it's hard to find info. I'm guessing mine was from dead base rock which I cycled with phosphate remover for two months. My only guess was that it started leaching out after several months in the tank. My alkalinity climbed
almost two points over a week I tried to keep up by doing water changes that was futile then I had to finally resort to adding murattic acid to the tank a few milliliters a day to keep Alk steady once I got it down to acceptable range. I lost many frag's of SPS during this time. Finally after about five months it stopped leaching.
 
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pharazon

pharazon

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Stop dosing them check over several days.

I had the same issue. Yes, it's hard to find info. I'm guessing mine was from dead base rock which I cycled with phosphate remover for two months. My only guess was that it started leaching out after several months in the tank. My alkalinity climbed
almost two points over a week I tried to keep up by doing water changes that was futile then I had to finally resort to adding murattic acid to the tank a few milliliters a day to keep Alk steady once I got it down to acceptable range. I lost many frag's of SPS during this time. Finally after about five months it stopped leaching.

Yeah, we stopped dosing and it still hasn’t dropped. Doesn’t appear to be rising which is good for now I suppose. I did order a Salifert kit to rule out the Hanna being faulty or bad reagent.

I’m sorry to hear you lost coral to the problem. Glad to hear it eventually stopped.
 

MnFish1

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It would be good to know - what you're calling an 'Increase'. 8--->10 is an increase 8 ----->8.1 is not. you may be chasing numbers. Also - how many gallons is your tank and thats in it. Most people here (I think) would say if you're going to dose - its best to use a pump continuously - rather than daily. But I may be wrong
 
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pharazon

pharazon

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It would be good to know - what you're calling an 'Increase'. 8--->10 is an increase 8 ----->8.1 is not. you may be chasing numbers. Also - how many gallons is your tank and thats in it. Most people here (I think) would say if you're going to dose - its best to use a pump continuously - rather than daily. But I may be wrong

I supposed I made a mistake with the thread title. Increase was less than 1 dKh. My bad.

The issue I am having is that alkalinity consumption appears to have stopped completely, as I stopped dosing for 4 days and alkalinity did not drop, while appearing to have increased. The increase may be testing variance. Regardless, alkalinity is not changing at all despite not dosing.

This in spite of visible growth of several SPS corals.
 
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pharazon

pharazon

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did you change anything else that would affect growth and thereby consumption? lighting, temp, other levels?

PO4 dropped from 0.10 to 0.03. That has been the only change in parameters.

Corals still growing. I photograph the tank a lot, and can visually confirm that multiple acros are encrusting. Two monti caps also growing considerably.
 
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