kalk reactor diy or buy?


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So I have spent many hours researching kalk reactors. Most that are premade seem to be simple with a giant price tag. Many diy have good ideas, some are extravagant, wasting time, money, and possibly less effective(but look great, sophisticated, units...for people with space. From what I have learned: Must be as airtight as possible. Must be dosed slow! Important not to get particulate into tank....must settle before pumping. and systems with large volumes is opinionated.

I already have extra phosban reactors I dont use. Wondering how it would work with one of these. It is pretty air tight, water enters from the bottom, making it soak up some kalk, some of the media filters included will stop some particulate, not all, but low flow shouldn't cause too much. I know the volume is small but I am not convince it has to be huge. Another thought was to have 2 reactors inline which will probably help with the particulate problem. I did notice tlf already makes their own kalk reactor, but haven't had time to research them.

My tank is a 125g and was planning on running this with my auto top off and aqualifter pump. Any thoughts if this will work ok? Opinions on pro's and con's. or should I just buy one(doesn't seem to be worth the money)...and after seeing so many manufactured, seems over the last 7 years design hasn't changed....other than less use of a magnetic stirrer. Even drippers seem to have worked good since they started, just more maintanance.

One more thought, is night dosing really worth the effort? from my understanding the ph does drop in most systems during the night, doing the kalk at night can help balance but is it a big benefit?


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I thank it is better to mix kalk in a container let it settle and then hook it up to your ATO. There is a less chance of adding impurities to your tank.


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I use two aquamedic stirrers and I love them. They constantly stir the kalk very slowly so there is no chance that the powder will get kicked up enough to make it out the top. When I bought mine they were only 189.00 But now they run like 230 or so last I looked for the exact same stirrer. I think they are still worth the asking price. I like a reactor just cause I only have to mess with lime about twice a month vs every day.


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I tried the "flow from the bottom mixes" DYI with a 10" ro/di filter canister set to run in reverse, with some hand-made filter discs.

I was never completely happy with it, and ended up making a pump stirred DYI out of 4" black ABS from the hardware store, and a MJ 400.

This works much better, and was about $25-30 in materials, plus a set of NPT taps for $36 bucks off the internet (1/4", 1/2", 3/4", etc) to tap the boday for the 1/2" to JG fittings I used.


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seawandrr, What were you not satisfied with? ty for the post, might help me stop attempting my idea.

My tank is a 125g with evap rate of abought 1.5g a day, and a pretty low calcium demand.

As of right now I have 2 options
#1: using my old 6g container from my oceanic salt mix. It has a rubber seal on top of the lid, I assume it is pretty airtight. Was going to use this with my mix and let my aqualifter and ato do the work. I would have to do kalk mixes every 3 days.
#2: Try using them phosban reactors....which are collecting dust. For some damn reason I think it should be simple and ez to use and be effective, and I already have a custom bracket in my sump for 2 reactors. In this setup I would still use the 6g bucket for the r/o water, it would be used by the aqualifter/ato and pumped thru 2 reactors. Only problems I see is with bad saturation quality. If I used 2 inline I should be able to see kalk deposits in the second if any pass thru the 1st(2nd should have enough time between cycles to let the water settle. Just to be safe making custom 100-300 micron disks might be a good idea in the second. In a high demand system this would probably not work too great, using the second reactor(in my opinion)can give a decent quality check? tlf is marketing a kw reactor similar to the phosban...that was a pretty good product, simple and cheap. Their kw reactor seems simple and cheap too. just can't seem to find reviews, and hate the mine is better than yours type.

Someone needs to make a post telling me this is a retarted idea, and tell me to stop wasting my time.......and yours


New member
Sorry, I should have been more specific in what didn't work.

I ran a piece of 1/2" PVC down to the bottom, then custom drilled an end cap to have distributed flow to flow up through the kalk.

With the flow from an aqualifter, it always ended up clumping and channeling after a few days.

So I tried more flow from a smaller MJ, which helped with the clumping, but I ended up fighting particulates in the tank.

So, it made more sense to switch to using an MJ to mix the kalk/water, and then I switched to an old masterflex peristaltic pump I had on hand to slow down the delivery, and make it more accurate. It pumps at the rate of 1oz per 10 minutes. This is why I DYI'd a purpose built 4" x 24" ABS reactor to handle this new scheme.

My reactor holds about 1.3 gallons (minus space for kalk). My inlet is 1/2 way up, so there is a bit over .6 gallons of saturated water available between the inlet and outlet at the top. (or about 60oz)

At 6oz per hour, I conservatively stop it ever 6 hours, mix, and then restart delivery after 1/2 hour of settling time.

I think you'd have the same channeling/clumping problem with the TLF. (I've got a couple of pairs running carbon/gfo, so am familiar with them) but I haven't tried it myself. It'd be 1/2 a cup of kalk and a couple of days of watching to see if you has the same problem.
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New member
in your opinion how bad was the clumping? once the kalk started running low it would dissolve somewhat anyways? Just curious to know what brand you used...if that might of not contributed to it?

off topic but I read you use them for carbon also...if you don't mind answering these question. how long? how often? what brand media? flow you use? and do you do before water change or supplement after.

thanks again...much needed info and am greatful for it.