What's going on with my Kalk Stirrer?

[special-ops-s2k]

Hello!

I have an Avast Marine Kalk stirrer and am feeding it rodi from my top off barrel at a rate of 12ml/min using a Kamoer FX-STP. I set this reactor up about 2 months ago and added a additional PH probe in the reactor to help gauge if it was saturated. I realize that PH isn't the ideal way to test saturation, but it's what I'm using at the moment...

Regardless, the first few weeks I would see a steady PH of 12 in the reactor, when it would drop to 11.9-11.8 I would add a scoop of Kalk and it would go back to 12. I recently cleaned the reactor for the first time, then refilled it and got a PH of 12... But it seemed to immediately drop off and within 24hrs was down to 11.3!?!? So I added another scoop and again it goes to 12 then within 24hrs is down to 11 3-11.4? I've repeated this 3-4 times now.

What is going on? What could be causing it? I have seen a few bubbles in my feed line, could that have anything to do with it? I don't know what is going on... Thanks

 

[garbled]

Have you tried setting the probe in the main tank to make sure it hasn't lost it's mind? Like just set it in there and check that it gives the same reading as your reef? FX-STP running at the same rate as always? Stir config still the same?

 

[special-ops-s2k]

Have you tried setting the probe in the main tank to make sure it hasn't lost it's mind? Like just set it in there and check that it gives the same reading as your reef? FX-STP running at the same rate as always? Stir config still the same?

I haven't recalibrated or checked the pH probe to rule out it being out of whack somehow... I'll do that tomorrow. The FX-STP is running at the same rate as always... I moved it around a bit at first to match my evaporation but it's been set at 12ml/min since before the mysterious drops started. I don't know how the Kalk can be losing potency so fast? And I'm not running nearly as much water through the reactor as it is supposed to be rated for? I'll check the probe and report back!

 

[garbled]

Oh, did the probe dry out while you were cleaning? If so, that can damage the probe. Usually when I clean my reactor, I drop the probe into the sump, to kinda rinse it, keep it wet while cleaning, and do a little check on it's sanity all at once.

 

[rmurken]

My first reaction was also “probe.” But then I caught up to your evaporation rate: 12ml/minute? That seems like quite a bit. How big is your system?

 

[rmurken]

Also: saturated kalk solution should be a pH of 12.4 or so. 12 would be a bit low if you’re going for saturated kalk.

 

[special-ops-s2k]

Oh, did the probe dry out while you were cleaning? If so, that can damage the probe. Usually when I clean my reactor, I drop the probe into the sump, to kinda rinse it, keep it wet while cleaning, and do a little check on it's sanity all at once.

I don't think it did, but that's a good idea for the future!

My first reaction was also “probe.” But then I caught up to your evaporation rate: 12ml/minute? That seems like quite a bit. How big is your system?

I have a roughly 250g system.... 4.5ish gallons per day of evaporation, give or take. I started with the FX-STP running 4ml/min and upped it every day until my ATO was only kicking on once or twice per day. I settled on 12ml/min as pretty close to my max evaporation

Also: saturated kalk solution should be a pH of 12.4 or so. 12 would be a bit low if you’re going for saturated kalk.

That's good to know! I definitely must not be getting anywhere close to saturated Kalk solution out of that reactor. It has bumped up my PH, but ever since it's been doing this drop off thing it's not keeping my PH up nearly as much as it was the first month or so. I'm confused!

 

[garbled]

I really don't get it.. thats odd. My money is on the probe maybe, but it could also be the brand of kalk you are using is not as good, the water you are refilling the reactor with is high in CO2, so less kalk gets in, maybe you just aren't putting enough kalk in? My guess might be the water you are refilling with has more CO2 or something in it interfering with the kalk? At your feed rate, how much kalk do you put in the reactor on refill?

So a side note. I'm one of the biggest pro-kalk people out there, but I would be super-careful running your kalk feed at near-evap rate like you said. The closer you get to the evap rate, the closer you are to having a flood because the evap was just lower today, or your water change was off by a bit. I would feel safer if I had a bunch of high water level probes on the sump with apex stuff to shut the kalk feed down, but still.. If you trust your high-water code/system, then yeah, it's probably fine.

And do not put a float valve on the end of the kalk, just in case, kalk will clog that super fast.

For my K2, my plan is to drill a hole in the top, and put a float swich in right next to the pH probe, because I had a tiny flood when the kalk output clogged a little and the reactor overflowed over the sides.

 

[C. Eymann]

Something to consider,
Stirrers arent usually sealed like reactors are, and will allow the solution to react with CO2 in the air.
Not saying thats exactly the reason for the pH drop, but its something to think about.

 

[special-ops-s2k]

I really don't get it.. thats odd. My money is on the probe maybe, but it could also be the brand of kalk you are using is not as good, the water you are refilling the reactor with is high in CO2, so less kalk gets in, maybe you just aren't putting enough kalk in? My guess might be the water you are refilling with has more CO2 or something in it interfering with the kalk? At your feed rate, how much kalk do you put in the reactor on refill?

So a side note. I'm one of the biggest pro-kalk people out there, but I would be super-careful running your kalk feed at near-evap rate like you said. The closer you get to the evap rate, the closer you are to having a flood because the evap was just lower today, or your water change was off by a bit. I would feel safer if I had a bunch of high water level probes on the sump with apex stuff to shut the kalk feed down, but still.. If you trust your high-water code/system, then yeah, it's probably fine.

And do not put a float valve on the end of the kalk, just in case, kalk will clog that super fast.

For my K2, my plan is to drill a hole in the top, and put a float swich in right next to the pH probe, because I had a tiny flood when the kalk output clogged a little and the reactor overflowed over the sides.

All good points, especially the float switch in the Kalk reactor. I don't have any protection from that point of failure, good idea!

As far as my feed rate, my ato still does run a few times daily, and I have an ATO HIGH optical sensor plus a SUMP HIGH sensor... If the ATO HIGH is closed for too long it kills the power to the FX-STP, if the SUMP HIGH sensor is ever closed it does the same thing. So I SHOULD be ok on the evaporation being too low one day and accidentally overfilling. I also have a overflow on my sump hard plumbed to the drain stack in my house so it can never overflow, albeit it could dilute to the point that my salinity drops but still that would have to bypass both my high level sensors...

I'm definitely adding the float valve to my Kalk stirrer, I don't want to have that flood in my filter room. For brand of Kalk it's BRS, it's an older zip pouch and I'm down to the bottom of it. Maybe the power was exposed to air too much and lost potency? I can try a fresh bag?

Thanks for brainstorming with me, I just couldn't figure out what was going on! I've never used a Kalk stirrer before but I've used Kalk on lots of systems in the past. This was a new one for me...

 

[rmurken]

Oh, one last thing: a more definitive way to test whether your kalk is saturated is conductivity. One of Randy’s articles on Ca/Alk supplementation has the gear and numbers you’d be looking for. Concentration drops off quickly with pH.

 

[special-ops-s2k]

As an update:

It appears the problem was old/improperly stored Kalk powder. The zip pouch wasn't sealing properly and that allowed the Kalk to be exposed to air. This apparently caused it to lose its potency. I switched to a new pouch and the results were immediate. As shown in the photo the Kalk would immediately start dropping in potency, after the switch to new powder source it is back to the way it used to be!