$40 DIY Kalkwasser Reactor for RO-fed ATO

[toomanytanks]

I just wanted to share an easy DIY project that provides a cheap alternative to expensive kalk reactors. Depending on where you source the parts and what parts you already have lying around, this should cost ~$40 to build. It is a reliable, and professional-looking system that you can't mess up. This kalk reactor is plumbed into my RO outlet ATO that is always on. You could just as easily plumb it to a solenoid and powering a powerhead from a separate RO ATO reservoir. This system mixes 000 TDS RO water with Kalk and then feeds it into a float valve placed in the sump of my display.

***Before you go bashing me for running limewater through the narrow 1/4" tubing and then to a float valve (which would easily clog the system), know that the limewater - although saturated with a PH of 12 - is mostly clear and does not contain the big chunks of white lime that usually cause clogs.

Parts list:

• 1x Clear 10" filter housing ($20 on eBay shipped)
• 2x 1/4" threaded/push to fit connectors (<$1 at HomeDepot)
• 2x 1/4" shut off ball valves (~$5 at HomeDepot)
• Various check valves (at your discretion) to keep the water flowing forward (<$1)
• 2x 1/4" push to fit 'T' fittings (<$1 at HomeDepot)
• Kalk/Lime ($
• RO Tubing (Negligible)
• 1x 5-6" length of 3/4" PVC (~$1 at HomeDepot)
• 1x 3/4" PVC cap (<$1 at HomeDepot)

Total Cost: ~$40

Tools:

• Power drill
• PVC glue (Blue 'Rain' or 'Wet' type)
• Teflon tape
• RO tube cutter

Instructions:

1. Lay out all of your parts on a flat work space and make sure you have everything you need, including tools.
2. Use teflon tape to go over the threads of your 1/4" threaded/push to fit connectors.
3. Slowly thread the 1/4" threaded/push to fit connectors into both ports on the filter housing until snug.
4. Open filter housing and turn the top over. You will see a small 'nub' or 'nipple' where you will attach the 5-6" PVC stem. Apply glue to one end of the 5-6" PVC pipe and attach it to this nub. Turn the PVC pipe 1/4 turn and let cure for ~10 minutes.
5. While waiting for the glue to cure, use a very small drill bit (the smallest you have to increase pressure of the output water) to drill a hole in the center of the 3/4" PVC cap.
6. Apply glue to the other end of the now-attached PVC stem and attach the 3/4" PVC cap. Turn the cap 1/4 turn and let cure for ~10 minutes.
7. Insert kalk into clear filter housing so that it covers the tip of the stem which is the 3/4" PVC cap.
8. Connect all RO tubing. Make sure you connect the output of the RO to the 'out' port of the filter housing and then connect the float valve side to the 'in' port on the clear filter housing. This is counter-intuitive, I know but, it must be plumbed this way for the filter housing to be used correctly in this application.
9. ***See diagrams and pictures below to see where I attached to valves, tees, and check valves.***

Pictures and Diagrams:

RO Tubing Route Layout:

Incoming water splits into a 'T' with ball valves on either side. After the valves, one side goes into the reactor and one side goes around the reactor. The one that goes around the reactor connects with the output of the reactor by means of another 'T'. From here, the water finally enters the float valve. This is to create a bypass. The purpose of the bypass is to adjust the amount of pure RO mixing with the kalk and the amount of pure RO going directly into the sump. If your evaporation is high and you have all or most of your RO ATO water reacting with the kalk, your PH could rise to unsafe levels and do serious damage to your tank inhabitants. Having these valves allows you to regulate if you want 100% pure RO top-off, 80% pure RO top-off and 20% kalk top-off, etc.


Another view:


Kalk first added and initial mixing (note the cloudy top layer of water above the condensed bottom layer):


After kalk has mixed, saturated the solution, and settled (note how the top layer has gone from cloudy in the previous picture to clear now that it has settled):


Output to sump via float valve:


So that's it! It has been up and running for a few days now with no issues. My Ph is up (in good levels), my Alk is up, and my Calcium is where it should be. This reactor has no moving parts and is cheap and easy to build. Let me know what you think or if you have any questions.