I also had a leak where one of the CPVC pipes went through the coupling. It is very important that this be a very tight fit before you glue the pipe in place. Mine was not real tight. You should test fit the pipe to some test holes. If it is too loose then file or grind the drill bit down a little until you get a tight fit. A drill press would give you more consistant holes but since I didn't have access to one, I used a hand drill and a 5/8' wood bit (the type with the ears, like a pitch fork). Later, I was able to get a tight fit by grinding the bit down a little. I tried to fix this leak by globbing silicon sealant around the leaking joint. This was a dismal failure. The silicon did not stick to the PVC and it just pealed right off quite easily. So then I plugged off all but one hole in the reactor, applied some Weldon 16 to the bad joint and sucked it into the leaking joint to give a good seal all the way through. This is holding well so far.

The Maxi Jet 1200 is way overpowered for this application. If I built another reactor, I would probably add a valve to control the recirculation rate. I may add an air bleed valve in the future. I tapped threads for the input and output hose barbs. I should have tapped the hole for the recirculation pump input line as well. The lower mixing portion of the reactor need only be big enough to see that the kalk solution is mixing properly. When I made my reactor bigger, I enlarged both the top and bottom sections. I should have just enlarged the top section to further minimize any milky kalk from getting into the tank.

This version of a Nilsen Reactor was very easy to make and required very few special tools. The only tool I had to go out and buy was a 3/8' pipe tap for $6.50. I spent a total of about $60 on this project. I already had the Reef Filler 1000, the appliance timer, and the Maxi Jet 1200. This kalk reactor will require less maintenance than mixing kalk in a Rubber Maid container every 4 days like I did previously.

UPDATE, 21 FEB 00: I was having trouble with my pH going up to nearly 8.6 so I decreased the number of stirrings from 6 to 3 and the problem seemed to get worse. Then I decreased it to 2 and it got even worse, up to 8.7. I finally discovered that when I put the on tab and off tab right next to each other on the timer (15 minute interval) that the off tab usually did not catch and shut off the pump so it was stirring the kalk solution for several hours. The solution was to buy a digital timer from Radio Shack (Cat. No. 61-1060). It has 4 sets of on/off times. Now I'm stirring 4 times a day for five minutes at a time and total cost of the project has increased to about $85.

UPDATE, 18 APR 00: I've had the reactor going since early February 2000. For the first two months of operation, I added about a weeks worth of kalk to the reactor at a time (about 10 table spoons). I would add another 10 scoops of kalk to the reactor when I noticed that the pH in my tank was starting to drop (about once a week or about every 12 to 15 gallons). It's been doing a great job of keeping my Ca at 400 ppm, Alk at about 3-4 meq/L, and pH at 8 to 8.4 with no other additives to the water except food and water changes.

When I first put the kalk in the reactor and fired it up back in February, the mixed solution and precipitate were quite white looking. Over the first two months it was running, this precipitate got progressively more and more brown looking. At first, when the tank pH began to drop, there was very little precipitate left in the reactor. Eventually, there was a substantial amount of brown precipitate left in the reactor when the pH began to drop but there was no noticeable side effect to the tank.

After the first two months of operation and with all that brown junk accumulating in the reactor, I decided it was time to clean it out. When I fired it back up, I decided to add about a half pound of kalk to the reactor instead of 10 table spoons and haven't opened it since. That's got to be about 3-4 months worth of kalk. Its been working fine for about two weeks now with the massive amount of kalk added at one time. The only kalk I have used for the last year is Ball Pickling Lime from Walmart.

UPDATE, 6 JAN 01: The Maxi Jet 1200 mixing pump finally failed. It lasted almost a year on the reactor and was actually over a year old before I put it on the reactor (see the coraline algae on it). The plastic impeller was very worn and is what failed. The metal shaft was also very worn. I have replaced the pump with another brand new Maxi Jet 1200. I probably could have just replaced the impeller but Maxi Jet 1200's are cheap and I had one laying around. There was no calcium build up in the pump at all. It was very clean but very worn. I did not seal the new pump with silicon and it is not leaking (yet!) I expect it to eventually start leaking. I am still using Ball Pickling Lime from Walmart with good results. After a year of using the reactor, I'm am very pleased with this design.

UPDATE, 24 FEB 02: A year has gone by since replacing the failed pump and everything is still working great. I never sealed the housing on the new pump with silicon and still no leaks.