Why Am I Burning Through So Much Alk?

[Spieg]

In the summer I run an air line from my skimmer intake to an outside air source. I use the fireplace vent because it is closer to the tank than any window (and I don't use the fireplace in the summer anyway)... keeping the small vent open is not enough to cause cooling problems in the house since it is only a few inches in diameter (much smaller than an open window). If you don't have a fireplace you could crack a window 1/4" for the airline and use some weather stripping to block the part of the opening that is not used for the air hose.

 

[rmurken]

Two thoughts to add for whatever they’re worth:

1. Are you certain that your pH readings are correct? Check calibration on your probe, etc.

2. For Ca/Alk, have you considered using whatever amount of kalk your evaporation rate will support? Kalk will soak up more CO2 on the way to equilibrium than a carbonate product.

Second all the comments about a skimmer and gas exchange.

 

[robbyg]

Thanks, yes I have a wave maker and a skimmer for aeration, and the skimmer air line is hooked into a recirculating CO2 scrubber, but my skimmer is pretty crap and inconsistent--can't really replace it because it's the only thing that will fit in the chamber of the Fluval.

You need to get some outside air into the system. IMHO this is a Co2 problem.

 

[Spare time]

Most two part products are designed for equal parts dosing, and take into account that alk drops faster than calcium (about 2.8 dKH for each 18-20 ppm of calcium)

Most two part products are designed for equal parts dosing, and take into account that alk drops faster than calcium (about 2.8 dKH for each 18-20 ppm of calcium)

OP is using Red Sea foundation which does not dose in even amounts

 

[Jonify]

Two thoughts to add for whatever they’re worth:

1. Are you certain that your pH readings are correct? Check calibration on your probe, etc.

2. For Ca/Alk, have you considered using whatever amount of kalk your evaporation rate will support? Kalk will soak up more CO2 on the way to equilibrium than a carbonate product.

Second all the comments about a skimmer and gas exchange.

Thank you ... yes, I've tested PH with 3 different kits. I don't use kalk because the Fluval doesn't evaporate much water ... ATO kicks on infrequently, so a gallon of topoff water lasts for a couple of of weeks. Both a design of the system, as well as the humidity in my apartment, which is extremely high. Opening windows makes it more so, and I have a dehumidifier running 24X7. I am looking into more expensive fixes, like an exchanger for the HVAC, but at this point, keeping alk high seems the only feasible solution ... I'm just running into problem even trying to do that

 

[Jonify]

You need to get some outside air into the system. IMHO this is a Co2 problem.

I absolutely agree ... Co2 is extremely high in the apartment. The only reason I don't have the skimmer intake connected to outside versus the scrubber is that the air outside is also high in Co2 (though not as high as inside, of course), and the data suggests a higher boost in PH using scrubber to skimmer vs. outside air to skimmer. BUT, given my skimmer is also crap, I'm considering implementing what someone else above mentioned--a pump outside, with a line running to an airstone in my sump. I have two more expensive backup plans as well: 1) fitting my HVAC with an exchanger and 2) transferring my tank to something with a larger sump that can house an efficient skimmer.

 

[Jonify]

Update this morning: after stopping Red Sea Foundation and starting the recommended initial dosing All for Reef instead, I woke up this morning to find the tank still sitting at 10.5dKH, 7.72pH. This is the first day where Alk has not fallen overnight, so this Alk problem seems to be associated more with the Red Sea Foundation quickly precipitating out (like many of you suggested) rather than my coral actually burning through several dKH a day. I plan to keep this dose for another day, then start slowly increasing until dKH is stable just above 11 or just above 7.8 ph.

 

[Jonify]

Oh boy. I have another update. Alk came up to 10.8, but my pH continued to slowly drop to 7.69. Remembering what @Randy Holmes-Farley mentioned, I thought "this is impossible." There is no way PH is falling this rapidly when alk is continuing to rise. Turns out, yes, this is impossible. I discovered this after running an API pH test, which showed about 8.1, compared to the 7.69 my Seneye is reading. So then I dug out my Apex probe which hasn't been connected because I'm running out of room in the sump, calibrated it through Apex local vs. fusion. Yes. 8.1. My Seneye must have sh&% the bed. I'm swapping out the slide now, and already, it's coming up closer to where the other tests show. When I responded to @rmurken above about having used several other test kits to validate--that was true--before I began raising alk. I hadn't attempted to re-verify after I began raising alk. I feel like an idiot.

So, in summary: 1) Why was I burning through so much alk? It was all precipitating out. Swapping to All for Reef fixed that, and at much, much lower doses. 2) Why wasn't I getting a bigger pH boost from increasing alk? I was, my Seneye just wasn't reading pH correctly. Currently getting 8.1 pH at 10.8 dKH. This is a number I am more than thrilled with.

(Re: 4 of my coral not doing so well, I caught my bicolor blenny taking a chomp out of my favia. I now suspect he is behind this.)

 

[rmurken]

Lol. Glad it worked out. I was about to suggest you talk to NASA or SpaceX about space flight-grade CO2 scrubbers.

 

[blasterman]

Jonify....I grow SPS like a boss in a 10 gal in an apt in a northern state and dont have braggable pH. Man you are creating a whole lot of work for yourself running that tip scalding dKH level.

Get your dKH down to 8-9, calcium in the 400 range and just use kalk if you want a pH nudge. End of problem and drama. Kalk alone can handle calcium and alk in a tank like that.

 

[Randy Holmes-Farley]

Oh boy. I have another update. Alk came up to 10.8, but my pH continued to slowly drop to 7.69. Remembering what @Randy Holmes-Farley mentioned, I thought "this is impossible." There is no way PH is falling this rapidly when alk is continuing to rise. Turns out, yes, this is impossible. I discovered this after running an API pH test, which showed about 8.1, compared to the 7.69 my Seneye is reading. So then I dug out my Apex probe which hasn't been connected because I'm running out of room in the sump, calibrated it through Apex local vs. fusion. Yes. 8.1. My Seneye must have sh&% the bed. I'm swapping out the slide now, and already, it's coming up closer to where the other tests show. When I responded to @rmurken above about having used several other test kits to validate--that was true--before I began raising alk. I hadn't attempted to re-verify after I began raising alk. I feel like an idiot.

So, in summary: 1) Why was I burning through so much alk? It was all precipitating out. Swapping to All for Reef fixed that, and at much, much lower doses. 2) Why wasn't I getting a bigger pH boost from increasing alk? I was, my Seneye just wasn't reading pH correctly. Currently getting 8.1 pH at 10.8 dKH. This is a number I am more than thrilled with.

(Re: 4 of my coral not doing so well, I caught my bicolor blenny taking a chomp out of my favia. I now suspect he is behind this.)

Thanks for the update!

 

[Jonify]

[Edit: changed "calcium carbonate/bicarbonate" below to "sodium carbonate/bicarbonate." Thanks, Randy!]

Update: tank alk/ph has remained stabled after switching from sodium carbonate to All for Reef (a formate). 10.8dKH, 8.1pH.

Something I found interesting: I started cycling a second tank around the same time, using RSCP salt (mixes to 12dKH), but alkalinity in the new tank did the same thing my main tank did ... slowly declined to the 7s/8s, then couldn't get it back up ... Red Sea Foundation B's sodium carbonate would just jack up the pH temporarily, then it would all just precipitate out and land even lower. I couldn't use All for Reef on it because it was connected to the doser on my main tank and I didn't want to keep moving it back and forth, so after a little more digging, came across several threads on issues with abiotic precipitation in new sand beds. One of the suggestions was to use a sodium bicarbonate buffer in new tanks, versus sodium carbonate. So I bought baking soda, diluted it in RO water, and began using that. Bam. Precipitation gone, alkalinity back up to 11dKH, and pH stable at 8.1.

So weird, I'm not sure why new sand beds cause a whole lot more abiotic precipitation than established ones, but for anyone else struggling with this in a newish tank, just swap to a sodium bicarbonate (baking soda, not baked) or a formate buffer, which is included in All for Reef, to get it back up to the right levels. It has worked for me twice now

 

[Randy Holmes-Farley]

So weird, I'm not sure why new sand beds cause a whole lot more abiotic precipitation than established ones, but for anyone else struggling with this with a newish tank, just swap to a calcium bicarbonate or calcium formate buffer to get it back up to the right levels. It has worked for me twice now

New sand lacks coatings of organic matter that reduces precipitation.

Just to clarify, you switched the alkalinity supplement from sodium carbonate to sodium bicarbonate, which is lowers the pH on addition and for a few hours later, and is one of the recommended ways to reduce precipitation of calcium carbonate. You were'n't using calcium bicarbonate or calcium carbonate as an additive.

 

[Jonify]

Just to clarify, you switched the alkalinity supplement from sodium carbonate to sodium bicarbonate, which is lowers the pH on addition and for a few hours later, and is one of the recommended ways to reduce precipitation of calcium carbonate. You were'n't using calcium bicarbonate or calcium carbonate as an additive.

Ah yes thank you.

 

[blasterman]

Something I found interesting: I started cycling a second tank around the same time, using RSCP salt (mixes to 12dKH), but alkalinity in the new tank did the same thing my main tank did ... slowly declined

Unlike calcium alk is consumed to some degree via most of the biological processes in the tank, especially the biological establishment of gravel and sand beds.

Take a new tank with no coral and add fish or ammonia to start a cycle. Gradually dKH will start to decline, and depending on the bioload it can start to decline very fast. Again, I've had small tanks a couple months old eat up to 2 dKH per day with only soft coral until all the bacteria and colonies and algae blooms are done. I wish BRS would do one of their experiments on new tanks to show how unbalanced calcium and alk is in a new tank.

 

[wrasse hole]

3 dkh of demand in a nano tank isn't unheard of. I dose around 3 dkh in my 20g nano, but I also have more coral than you.

Is your tank growing lots of coralline algae? Otherwise I would guess you're experiencing precipitation. You should try dosing more evenly throughout the day to avoid this. An auto doser really helps here. As previously mentioned, 2-part is designed to be dosed in equal parts. I've always dosed in equal parts and have never had an issue with a Ca/alk imbalance, although I still test calcium every few months to make sure.

Also, you mentioned your demand dropping after changing dosing methods. Don't be quick to attribute this to a fault with the old method since tanks often lose demand after changes are made that upset the corals.

 

[Jonify]

Again, I've had small tanks a couple months old eat up to 2 dKH per day with only soft coral until all the bacteria and colonies and algae blooms are done. I wish BRS would do one of their experiments on new tanks to show how unbalanced calcium and alk is in a new tank.

Yes, agree ... this is important stuff for newer reefers. One one hand, you could advise patience and hands-off approach to newer reefs until things begin to mature and you can get a better sense of balanced consumption, and on the other, for those who might be moving corals over into a new reef, or who use an elevated levels salt for water changes, or just who don't have the option of hands-off in those first few months, it would be nice to know what the right tool is for the right job [hey there @BRS], during that first period.

 

[Jonify]

Also, you mentioned your demand dropping after changing dosing methods. Don't be quick to attribute this to a fault with the old method since tanks often lose demand after changes are made that upset the corals.

Good point--I think in my case, 3dKH turned to 4, then 5, then 8 (over a span of a few days), with each rapid fall happening over a period of an hour or two, not a whole day, then a cloud of precipitate on the water's surface ... all just points to what several of the others said. (One interesting thing I saw, if I dosed the carbonate, the exact time it took to complete the whole dose is exactly the time it took for alk to drop back down to where it was, or lower. So if it took me 2 hours to complete the dose, 2 hours later, it would be back down where it was--which led me to the assumption that it was all precipitating out exactly as quickly as I was putting it in.) After swapping, alk has remained steady, consumption is just under 1dKH a day, and pH stays locked on 8.1, even at night.

 

[Jonify]

sodium bicarbonate ... which is lowers the pH on addition and for a few hours later ...

Yes, I've noticed that a daily dose of 1dKH to maintain 11 dKH lowers pH about .03, which for me is 8.1 to 8.08pH, for about 4 hours, then goes back to 8.1 around the 5th hour ... a negligible drop, compared to the pH spike of carbonate. On balance, bicarbonate seems quite a bit more stable than carbonate, at least for my specific application.

 

[Randy Holmes-Farley]

. On balance, bicarbonate seems quite a bit more stable than carbonate, at least for my specific application.

Perhaps it is just your wording, but I think that statement is a bit misleading. Seawater contains both bicarbonate and carbonate and you have no control over the ratio of the two except via pH. What you add makes little difference to what ends up in the aquarium after it mixes in. The reason one may have some precipitation with higher pH additives is that the local pH is higher, shifting more of the bicarbonate to carbonate locally until it mixes in.