Designing a kalk "stirrer"

[dandy7200]

I would like to build a simple bar stirrer for kalk. Similar to the Deltec or the Aqua Medic. Of course this needs to hang on the side of my sump which neither of these major brands offer, this should eliminate any "infringement" issues from this discussion .

My understanding of these is that there is a gravity flow and the vessel is not under any pressure. The lid is simply a lid and does not need to be water/pressure tight. The motor is variable speed and I believe max RPM is about 10. The water inlet/outlet goes through the same fitting on the reactor. Heres a quick picture for referance:



Right now I am looking for motor suggestions, speed controller suggestions and ideas to improve on this design. The chamber is not airtight and some feel that this is important although I have not heard much complaining going on with those that have the reactors pictured above. Another alternative to the same idea is this design by Spazz:





On this design the JG fitting in the lid is for kalk out, the top JG fitting on the pipe is for RODI in and the bottom JG fitting on the pipe is do drain water from the reactor to make a slurry and pour back into the "funnel" at the top of the pipe. There is a acrylic disc that sits inbetween the union and the funnel to seal it al up. This design looks a bit better as far as air contact is concerned but, more likely to leak and more complicated to build.

I would like to hear you thoughts on these designs and point me in the right direction.

[dandy7200]

This is a AC motor from Mcmaster:

6142K4
Single-Phase Subfractional-hp AC Gearmotor W/Fan, Face Mount, 10 rpm, 40 In-lbs Torque
$43.38 Each

Is this whe right way to go? Benefits of AC or DC for this application? Cheap speed controller?

[dandy7200]

How much torque do I really need? If I went with this:

6142K5
Single-Phase Subfractional-hp AC Gearmotor W/Fan, Face Mount, 20 rpm, 25 In-lbs Torque
$43.38 Each

I would have more speed control, but I don't know how much in-lb I need to churn a few cups of Kalk.

[dandy7200]

Surplus center has one similar to the first w/ no fan for $9.95 here.

[dandy7200]

For shaft 1/4" id 1/4" thick cast tube from Mcmaster is:

8532K12
Extruded Acrylic Hollow Rod 1/2" Od, 1/4" Id, 6' Length
In stock at $3.75 Each

Reactor Body

6" x 24" (have this)

[dandy7200]

After consulting with spazz, this is the motor I now plan to use.

35 RPM gearmotor

35 RPM, 24 DC


• New MOLON take-offs. Inline parallel shaft gear motor. Rated 24 volt DC, will run on 12 volt DC at lower speed and torque.
SPECIFICATIONS
• RPM 35
• Voltage 24 DC
• Draws 175 mA @ no load
• Torque 38 in. lbs. full load
7.5 in. lbs. cont.
• Rotation reversible
• Duty continuous
• Shaft 5/16" x 3/4" long w/flat
• Mount face 2 3/8" x 2 1/2" drilled/tapped
• Size 2 3/4" x 3" x 2 3/16"
• Shpg. 2 lbs.

[dandy7200]

You guys are welcomed to participate in this if you like

[rdmpe]

Have you considered a kalk reactor without a stir mechanism, where the water enters from below and travels through the powder? Here's a thread on one way to do it
http://archive.reefcentral.com/forum...00#post8279000
I'm going to do one that way to start. A conductivity meter such as a poinpoint salinity monitor can be used to measure the limewater strength exiting to verify that it is saturated (or not). I have a dual canister water filter that I'm going to be taking out of service, so it is practically free for me to try this first...

[kentrob11]

That motor looks good to me. No having to seal the top makes it a fairly easy project IMO.

[dandy7200]

rdmpe, I have considered the other styles and really wanted to do this one for a couple reasons. First of all I can't find any information about people building a similar one here on the diy forum with the exception of spazz and his is even pressurized with the kalkwasser coming out the lid (read I like to try new things ). Second, every comment I have ever read about the deltec stirrers is that it is pretty much failsafe and the is no way to fry your tank with that design (read I have to much $ invested in my tank to ignore those statements ) I can understand though wanting to try that one if you already have the parts.

kentrob11, I really do think it will be quite easy to build, actually the PDF for the km500 has an unbelievable amount of design detail that is provided. I'm not going to put it on this thread, others that may read this in the future shouldn't have too hard of a time tracking the product manual down.

I am looking still for a inexpensive way to control the motor speed. The cheapest thing I have found yet is one like this.
$31 shipped is not that bad but, it's HUGE. I really doubt I need infinate controll over the voltage, maybe 3v, 6v, 9v, 12v would be enough and I don't think I need to go up to 24v either. Anyone have any ideas on the speed contol?

[alpine]

What about useing a speed controller for a router?Heres a link to one that HF sells. http://www.harborfreight.com/cpi/cta...emnumber=43060 . Not sure if this is what you are looking to use,but it could put you on the right track.It basically controls the voltage going to the router.More voltage the router spins faster,less voltage and the router spins slower.Which is what it sounds like your trying to do.Bet you could probaly snatch one off ebay for cheap.HTH

Alpine

[Lunchbucket]

anymore info on spazz's design?

where you get those pics? there a thread?

Lunchbucket

[dandy7200]

Thats a good idea. After looking though it seems that I would need a dc power supply as well. This is why initially I wanted to use ac motor so I could just put a dimmer on it but, in the long run I think for safety reasons the dc is smarter even if it cost a few extra bucks on the frontside.

[alpine]

What about useing a speed controller for a router?Heres a link to one that HF sells. http://www.harborfreight.com/cpi/cta...emnumber=43060 . Not sure if this is what you are looking to use,but it could put you on the right track.It basically controls the voltage going to the router.More voltage the router spins faster,less voltage and the router spins slower.Which is what it sounds like your trying to do.Bet you could probaly snatch one off ebay for cheap.HTH

Alpine

[kgross]

IF you want to automate the speed controll, just use a simple wall wart transformer pluged into a dimmer (even an x10 lamp controller should work) as it trys to dim, the output from the transformer will decrease.

[scott324]

If you can find a AC motor a simple dimmer switch can be used to control speed. You can use a potentiometer to control the DC motor, but be aware that this is not the best way to do it and will create heat.

[dandy7200]

Well, after looking at potentiometer options, I decided to go with one of these.
Since I needed a power supply anyway it just made since to get everything in one package. $15 shipped is nice too.
I got the acrylic from e-bay as well and it was delivered today. I ended up with 6" diameter 1/8" wall extruded since this is not a pressure vessel. I also have some 3 1/2" tube that I may make a motor enclosure with. I think I may just gut the power supply and put everything in the top, the way that deltec does to keep it neet looking. I also got 1/2" acrylic rod to use as the stir bar. I have yet to decide how I want to make the bar. What do you guys think? Bent like the deltec or a fin like spazz or I was also thinking of making a T with the rod instead of the paddle, that would probably be the easiest. To keep track, my cost on the project is about $80 and should end up being about $100 by the time I get all the misc. stuff to make it all come together, this also includes me buying 2 motors just incase one bites it, I like to have a backup since surplus is what it is.

[dattack]

What's the best way to attach the shaft of the motor to the stirrer?

[dandy7200]

I plan to drill the rod and use a set screw. That motor shaft has a flat side.

[garbled]

How do you seal the shaft at the top of the reactor? Does someone make a seal that can be used for that?

[dandy7200]

It is a gravity dripper so there is no need to seal the shaft. There will be about 2" between the water level and the lid.

[dhnguyen]

You do know that it's rather easy to DIY a magnetic stirrer right? Probably much cheaper to do it that way too.


http://brewiki.org/StirPlate

http://www.lce.org/equipment/stirrer/stirrer.html

http://www.shroomery.org/68/Do-it-yo...netic-stirrers

[dandy7200]

I have heard about 2 many mag bars failing. Never heard of a direct drive stirrer fail. The thing I like about this is the slow 24/7 stir rather than the whirling a couple times/day. Reality is , I just wanted to try something differant that I have not seen a bunch of times and its still going to be $300 cheaper than the big "D" brand.

[dandy7200]

Progress

[guido_kp]

cool. looks good. i think this will be my next project. i guess i dont fully understand the kalk concept, tho. i see that it is a very slow flow rate to the tank. most say that it should replace water at night (to counter the natural drop in pH). i guess what escapes me, is what the flowrate should be? how long should this guy run to top up? my tank usually only tops up maybe twice a night - and never in the daytime (the tunze wavebox raises the water level in sump by slowing down the overflow, so the floats never trigger the topoff) i dont want to run it so slow that it sucks the return dry before its finished topping off or run it so fast that it doesnt get enough contact time to do any good. what feed pump will you use? my ato has a mj400 - i guess this is ok, i can bypass the excess flow back into the topoff reserve, right? sorry for rambling but i just dont understand the flowrate.