High Tide Aquatics

Alk dropping 0.2-0.3/day?

IOnceWasLegend

Frag Swap Coordinator
BOD
So after getting an alk tester, I realized my alk was hovering in the low 7s. After bringing it up to 8, I realize I'm getting a decent drop in alk every day (0.2 to 0.25), compared to a drop of ~0.1/day when the alk was lower. I have no SPS, but a lot of LPS. I'm not overly concerned about this just yet, but curious whether the draw's more likely to be a coral hitting a growth spurt, or if there being a high enough concentration of alk is giving me a more accurate picture of my "true" alk usage.

Similar question: I have not gotten a calcium test yet. While I will be getting one sooner rather than later, is it a bad idea to dose alk without monitoring calcium?
 
Was just discussing this with a few fellow reefers.... our alk seems to be dropping this past week and we’ve had to keep increasing our dosing amounts to keep up. Other than the obvious possibility of a coral growth spurt, we’re somewhat baffled by the fact that we are all experiencing the same thing. Maybe it’s a seasonal thing?


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Was just discussing this with a few fellow reefers.... our alk seems to be dropping this past week and we’ve had to keep increasing our dosing amounts to keep up. Other than the obvious possibility of a coral growth spurt, we’re somewhat baffled by the fact that we are all experiencing the same thing. Maybe it’s a seasonal thing?


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My alk has been pretty stable drop wise... in that i throw a tablespoon of baking soda into the overflow every night and it keeps my alk right at about 9.8 +/- 0.2...
 
Was just discussing this with a few fellow reefers.... our alk seems to be dropping this past week and we’ve had to keep increasing our dosing amounts to keep up. Other than the obvious possibility of a coral growth spurt, we’re somewhat baffled by the fact that we are all experiencing the same thing. Maybe it’s a seasonal thing?


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Some random thoughts....

1. Did you recently have baby snails? Tons of baby snails can suck up alk like no other. I've seen them take 1dkh/day in a 90 gallon tank (actual water volume).
2. If your tanks are running hotter because it's getting warmer, alk consumption could possibly go up. Metabolism of all creatures increase in warmer temps.
3. Are you opening your windows more than before because of the warm weather? Opening windows will likely cause pH to go up and stony corals will grow faster.
 
what's that have to do with increased alk usage? And I think he has a IM20....Calcium reactor is a little overkill....

Sold the IM20 last year. Have been running a 70g since then. And you’re right... we have been opening the windows more and the ph has gone up a little.


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3. Are you opening your windows more than before because of the warm weather? Opening windows will likely cause pH to go up and stony corals will grow faster.
This is probably a big part. I knew higher ph was associated with higher coral growth, but i didn't really realize how big of a difference it could make in daily alk consumption. Reading this made me think. In the last couple weeks I have seen the opposite issue as the OP, my alk has been creeping up little by little even with no change in dosing. This seemed odd to me since over time generally alk goes down (consumption goes up.) So today I pulled my alk/ph reading over the last few weeks.

I have actually had my windows CLOSED more recently as it has been hotter, and my ph has been lower on average.

Blue and right scale is ph. Orange and left scale is alk.
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Might be time to look into venting the skimmer to the outside...
 
It’s normal to see more Alk usage at higher Alk, since corals usually respond to higher Alk with faster calcification rates. To your other question it’s probably a good idea to test and adjust calcium at least weekly.
 
Thanks for the input, everyone!

Some random thoughts....

1. Did you recently have baby snails? Tons of baby snails can suck up alk like no other. I've seen them take 1dkh/day in a 90 gallon tank (actual water volume).
2. If your tanks are running hotter because it's getting warmer, alk consumption could possibly go up. Metabolism of all creatures increase in warmer temps.
3. Are you opening your windows more than before because of the warm weather? Opening windows will likely cause pH to go up and stony corals will grow faster.

1. My nassarius snails have laid a ton of eggs, and my ceriths laid eggs a while ago, but I haven't seen any babies in the tank.

2. My tank's set at 78, and I've been watching the temp like a hawk; it's stayed within its normal range (maybe a slight tick up to 78.5 before it corrects, when the range for the past few months has been 77.8 to 78.4).

3. I hadn't considered that; I haven't been opening windows more frequently, but we've had the AC running more, which would be increasing gas exchange outside vs inside. The AC (wall mounted unit) is in the same room as the tank, so that's one possibility I hadn't considered. The corals have been looking a lot happier in the past week or two (since we started running AC/opening windows) so maybe that has something to do with it.

It’s normal to see more Alk usage at higher Alk, since corals usually respond to higher Alk with faster calcification rates. To your other question it’s probably a good idea to test and adjust calcium at least weekly.

Okay, good to know that's a potential consideration as well. I figured there was the possibility of alk uptake being limited by 'free' alkalinity concentration, so good to know that I'm not totally off-base on that. Until I start testing calcium, I'll probably compensate by upping water changes to twice a week to replenish both Ca and alk while keeping swings to below 1 dkh. Not overly concerned since most of what I have is super hardy, but I figure consistency is still key. :)
 
3. I hadn't considered that; I haven't been opening windows more frequently, but we've had the AC running more, which would be increasing gas exchange outside vs inside. The AC (wall mounted unit) is in the same room as the tank, so that's one possibility I hadn't considered. The corals have been looking a lot happier in the past week or two (since we started running AC/opening windows) so maybe that has something to do with it.
The A/C doesn't exchange inside/outside air, so that's likely not contributing. Opening windows definitely would though.
 
what's that have to do with increased alk usage? And I think he has a IM20....Calcium reactor is a little overkill....
Well he did say he doesn't have a calcium test yet, so chances are that's also being used quite a bit.

Out of curiosity to the OP are you dosing anything to try and keep it up? Or just doing water changes to try and keep it up? Also are you seeing a spurt of coraline algae growth? That can use a surprising amount of calcium and alkalinity, I'm currently going through the same boat where my alkalinity is dropping faster than my kalkwasser can keep up, but it's been warmer, more open doors/windows (no a/c in San Fran) so probably pH related, and yeah I'm seeing very visible montipora growth in the tank so more likely than not it's sucking up more alkalinity (which is really all I test for, I should test calcium too so I can use some soda ash and Ca++ to get it back in line quickly).
 
Woah, I thought ph that high was bad? How often do you have to change the scrubber media? That's the part that worries me...

I haven’t had issues with it being that high at all. Been running this way for a couple years now. I haven’t changed my media in almost 2 months. It’s all about how you implement.
 
Well he did say he doesn't have a calcium test yet, so chances are that's also being used quite a bit.

Out of curiosity to the OP are you dosing anything to try and keep it up? Or just doing water changes to try and keep it up? Also are you seeing a spurt of coraline algae growth? That can use a surprising amount of calcium and alkalinity, I'm currently going through the same boat where my alkalinity is dropping faster than my kalkwasser can keep up, but it's been warmer, more open doors/windows (no a/c in San Fran) so probably pH related, and yeah I'm seeing very visible montipora growth in the tank so more likely than not it's sucking up more alkalinity (which is really all I test for, I should test calcium too so I can use some soda ash and Ca++ to get it back in line quickly).

At the moment I'm not dosing anything to keep it up, as I know there's interplay between Ca++ and alk and don't want to throw that out of whack until I have a solid handle on what's going on. So I've been relying on water changes.

I've been keeping an eye out for coralline algae, but no indication it's growing yet (though my system is only 3 months old), so I don't think that's too surprising.

A buddy of mine (in a, "...well, DUH") moment last night also pointed out I'd also added a favia with ~8 or 9 polyps to the tank a couple weeks ago, so that could also be where a chunk of it's going.
 
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