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orcafood
09/14/2017, 03:40 PM
I must admit I am a bit shocked you are able to dose enough kalk to maintain your alkalinity. I assume you are doing it via topoff? Unless you are able to dose the powder form, accurately, and in a way that does not cause issues, I found in the past I didnt evap enough water to allow for enough kalk to keep alk up on its own.


"""I know this is off-topic and I should start a new thread, but""" I really, really want a good way to accurately dose dry CaOH2 to a reef tank. Ultrasound, gas carrier, pellets in a gumball machine setup, there must be a good way to accurately dose a powder into a liquid.

bertoni
09/14/2017, 04:59 PM
There are two issues with getting the powder into the tank. The first would be to find a dry-dosing setup. The next issue would be how the lime reacts to the high humidity that it'll likely encounter in a tank setup. Lime could spike the pH badly if the doser overdoes it, so I'd be careful.

Once you got that issue settles, you'd need to make sure that the powder dissolves and is distributed quickly enough to avoid precipitation as sand. I'm not sure how difficult that would be. If you're willing to dose into a large volume of water, like the display or a very large refugium, that'd reduce the odds of a problem.

I looked for powder dosing systems, but all the equipment I found seems to be laboratory or higher-volume oriented, and I suspect it'd be very expensive. Maybe there's a business opportunity for someone with mechanical skills. :)

karimwassef
09/14/2017, 06:03 PM
I run a very thick kalk reactor ~ 2kgs per run for ~ 2 months.

It's a cheap DIY.

orcafood
09/15/2017, 06:24 AM
I'll probably end up setting a kalk reactor up, I was just curious if anyone had come up with a good way. Glad you explored the options Bertoni :)

I was thinking an ultrasonic plate would be the best way, humidity is still a serious problem.. I will have to go find some of these ready made dry dosing units and research. A speaker head with caoh2 on it would probably very slowly release it into the air with the right frequency

karimwassef
09/15/2017, 07:13 AM
love the cool ideas, but why worry about humidity when a white kalk mud is immune since it's already submerged.

orcafood
09/15/2017, 07:28 AM
I was thinking about it since many people are not capable of handling their tanks alkalinity demand with CaOH2 alone. I figured if there was a good way to dose it dry and dissolve it into the tank it would make it easier to maintain a full sps tank to completion with just kalk. Also for me it would free up my two dosing pumps and allow me to use those for more interesting affairs like automatic feeding or nitrate dosing

karimwassef
09/15/2017, 07:36 AM
Dosing pumps are easier to manage than solid dispensers imo.

I broke a couple trying to keep up with my Alk demands so I switched to a passive RODI solenoid that feeds my kalk reactor. That overflows the clear kalk effluent into the sump.

It's very simple and a motor agitates the kalk mud at the bottom of my reactor to keep the clear water above it supersaturated. No monitoring required. All on timers.

There are smarter ideas to keep the "perfect" white/clear suspension but I never implemented them because the reactor worked without issue.

It's a DIY and cost me ~ $50 - mostly for the motor, solenoid and acrylic tube. The rest is plumbing.

orcafood
09/15/2017, 07:47 AM
How can kalk keep your system going but struggles with others systems?

Also, unrelated, but how do you get around your skimmer going nuts when you feed that huge tank?

I am right there with you. I already have an old 4 watt, 5 rev/min motor hooked up to a tube with an eggcrate stirrer ready to go, I just want to find the right container. Would a 5 gallon bucket be tall enough or do I want something way taller and skinnier like a piece of pvc?

karimwassef
09/15/2017, 08:28 AM
I run a very hot tank 82-84F and my evaporation is very high. The high temp accelerated my coral growth rate and my heavy aeration (injection) keeps my water flush with fresh air.

I don't use top-off, but I have no issue dumping in gallons of kalk effluent a day.

I don't have a skimmer. I stopped using one last year and converted to the air injector only.

check out my youtube channel. I have a bunch of vids there
https://www.youtube.com/channel/UCDz3Mpbp4B_T3jpfOeZ60Yg/videos

<iframe width="560" height="315" src="https://www.youtube.com/embed/ydYQXfrdlJU" frameborder="0" allowfullscreen></iframe>

<iframe width="560" height="315" src="https://www.youtube.com/embed/UdAnkP8qDqw" frameborder="0" allowfullscreen></iframe>

<iframe width="560" height="315" src="https://www.youtube.com/embed/bVxy1jna4S8" frameborder="0" allowfullscreen></iframe>

as well as new experiments

<iframe width="560" height="315" src="https://www.youtube.com/embed/18ZsggRjOPI" frameborder="0" allowfullscreen></iframe>

orcafood
09/15/2017, 08:31 AM
Ah you you can deliver extremely over saturated kalk water to your tank, so awesome. That water at the top is definitely not totally clear, but to keep up with serious demand why would you want it to be.

orcafood
09/15/2017, 08:32 AM
What are the dimensions on your kalk reactor?

nereefpat
09/15/2017, 09:57 AM
About the original topic:

Wouldn't adding dry CaOH to saltwater cause precipitation of calcium carbonate and possibly Magnesium hydroxide as well?

orcafood
09/15/2017, 10:17 AM
I would guess that it depends on exactly how much is added to the extent that hydroxides and carbonates are formed. Adding micrograms of calcium hydroxide to a rapidly mixing container of saltwater would be very different than adding milligrams. The high local pH is what would cause the precipitation events, so dispersing of the solid would be important.

I think that caco3 precipitation would be a good thing, lowering phosphate would be nice, but lowering magnesium would not be good. Have to wonder whether the caco3 being added would precipitate more carbonate from the water. But could it be overcome with enough addition of calcium hydroxide?

karimwassef
09/15/2017, 11:13 AM
My cylinder is 6" diameter and 2' tall.

Actually, the effluent is clear at steady state. Just need to wait after mixing

orcafood
09/15/2017, 03:32 PM
This is way complicated but I like the horizontal screw idea

https://www.youtube.com/watch?v=8J5PuQqPRMY

bertoni
09/15/2017, 04:05 PM
Wouldn't adding dry CaOH to saltwater cause precipitation of calcium carbonate and possibly Magnesium hydroxide as well?
Yes, that's quite possible. That's why I would recommend dosing into a large volume of water with a lot of surface motion, to distribute the Kalk quickly. People get slurries (like the setup pictured in this thread) to work, so dry dosing might, as well. It'd take some experimentation to see what happens, though. I might start with a separate setup with no animals, just saltwater, to see what happens. A 5g bucket with a powerhead probably would be fine.

bertoni
09/15/2017, 04:07 PM
This is way complicated but I like the horizontal screw idea

https://www.youtube.com/watch?v=8J5PuQqPRMY
That powder feeder is intended for continuous dosing. I'd worry about the Kalk solidifying and blocking the mechanism, given the likely high humidity of the surrounding air. I might be wrong, though. Have you checked the cost?

karimwassef
09/15/2017, 04:13 PM
Hey hey... who you callin' a slurry? :D

The bottom is mud, the middle is slurry, but I assure you that the top is crystal clear!

karimwassef
09/15/2017, 04:48 PM
By the way, I don't add acids or carbon sources... I like to keep all my hydroxides safe...

bertoni
09/15/2017, 05:31 PM
Hey hey... who you callin' a slurry? :D

The bottom is mud, the middle is slurry, but I assure you that the top is crystal clear!
Oh, I see. Well, others definitely have dosed slurries without problems, although all the cases I can remember were dosing by hand.

karimwassef
09/15/2017, 05:45 PM
I think the video shows it but there are a couple of "secrets" I use.

The three zones have different controls.

The propeller/mixer is just in the mud. It shouldn't extend to the slurry.
The RODI water injection should be at the bottom of the slurry.
The pump needs to run intermittently to maximize supersaturation without compromising the clear section. This "rate" depends on the volume of "mud" to water. For me, it was 30 seconds every 30 minutes. This was painstakingly determined experimentally.

But if I add more mud, or as the mud dissipated over time, this can change.

My optimization was to add an IR transmitter and sensor halfway up so that the motor only runs if the sensor is clear. This means that cloudy water would stop the motor and I don't have to think about it any more.

The last trick it to set alarms in case the kalk runs out... basically, I can keep my pH between 8.34 and 8.36 when all is well. But if my kalk runs out, I go down below 8.3... and everything stops! Otherwise, you end up with a flood and a freshwater reef :)

Just little tricks

orcafood
09/15/2017, 06:11 PM
An IR turbidity sensor is a great idea for controlling the stirrer, nice one.

Dosing a kalk slurry is exactly what I am starting to think might work. I really like the idea of using a screw to very accurately dose the fine kalk powder, everything could be sealed well and even some desiccants could be used in case. Perhaps a good way to do it would be to accurately measure out a small amount of powder, then have the ATO water run through the area where it dispenses and drag the slurry into the tank. Dosing a teaspoon (~4 g) of kalk per hour would translate into around 60 mg of kalk per minute. I bet a screw could easily do that with a controllable low rpm motor.

karimwassef
09/15/2017, 07:07 PM
If you can get it to work, I've been trying to get a salt dispenser to work for automatic water changes.

Same issue- humidity.

orcafood
09/15/2017, 07:15 PM
You should use a dedicated dehumidifier if need be. I would guess that a huge container of desiccant and sealing the vessel well would solve the humidity issue.

I bet it will all come down to a quality screw component and matching motor. Given that part the rest of this is easy?

It would be nice to have a pre-made plastic/ceramic screw assembly that was made to disperse free flowing powders. Making that will not be easy, it needs to be made with very close specs. Controlling the amount of time the screw comes on would be easy, or maybe just control the speed the screw turns?

Why not use multiple redundant IR sensors to track the turbididty of the kalk reactor effluent. That way one could accurately dose a certain turbidiity of kalk slurry, plus the heavier kalk slurry at the bottom will still help to filter out impurities. This takes out the possible error in the screw dosing the dry powder and the darn humidity factor. I can see how heavily dosing CaOH2 might start to require some CO2 dosing. Perhaps a mini CaRx run at a low pH to increase CO2. The zooxanthellae we are growing need very accurate dissolved *CO2 levels I think. That is why Karim's setup, constantly bringing CO2/O2/N2 works so well. Serious gas exchange forces the CO2 levels to be perfect.

orcafood
09/15/2017, 07:49 PM
That powder feeder is intended for continuous dosing. I'd worry about the Kalk solidifying and blocking the mechanism, given the likely high humidity of the surrounding air. I might be wrong, though. Have you checked the cost?

No cost check, I was mostly intrigued with the mechanism. Even my chemical engineering buddy was pretty baffled with this problem :)

bertoni
09/15/2017, 08:06 PM
It is an interesting issue to solve. I've had bad experiences even with feeders and humidity. Nothing drastic or damaging, but the feeders have been known to fail to feed. The food can stick to the mechanism. Sigh.

orcafood
09/15/2017, 08:21 PM
For the automatic feeder I was thinking a peltier unit could keep a pretty solid block of food cold enough to constantly run a drip from the return pump over the 'frozen food' and into the tank. That is another issue for another thread haha :) I have been really trying to come up with a way to dose frozen blender mush to my tank non-stop, not only could my skimmer balance out with the nutrient load but the coral growth would be unreal.

karimwassef
09/15/2017, 08:37 PM
You can DIY screws with 3D printing.

bertoni
09/15/2017, 10:32 PM
Peltier devices are interesting. They are very power-intensive, though.

orcafood
09/17/2017, 07:39 AM
If I was only good enough at blender to make models. I am good enough to make the shapes that I need but 3D models are more complicated than that. Needs to be a totally closed shape which is always the part of 3D printer modeling that goes over my head. Not to mention all the necessary supports which are not easy to add into models, remeshing is a b. I have access to a 3D printer through NCSU, I may just need to start trying it out.

orcafood
09/17/2017, 07:40 AM
Peltier devices are interesting. They are very power-intensive, though.

A mini compression freezer would be oh so lovely.