We have a couple of Victoria Amazonica Lilies in our pond - the ones with thorns up to 1" long. These require a LOT of fertilizer tablets - up to 12 at a time. I have been putting them in by hand, but I need to kneel down in the pond in three feet of water. And constantly get poked, prodded and cut by the thorns. Even the small lilies are a pain, as there are so many. I could not find anything under $40 that allowed me to sink the tablets in the submerged planters/pots, so I made this.
Since the pond fertilizer tabs are about 7/8ths across, I used 1" PVC for the sleeve and a 1" wooden dowel for plunger. It's just over 3' long which is ideal for my use. You can make it shorter or longer.
The idea is to sink the tablet in the dirt a few inches.
Step 1: Cut and Shave the PVC.
Simply cut a section of 1" PVC to the desired length. If need be, sand the cut end smooth and clean. One end will be the "spike" that gets pushed into the dirt. I used a file followed by sanding to form the end into a cone shape.
Step 2: Cut the 1" Wood Dowel and Finish It
Cut the 1" wooden dowel about 8" longer than the PVC. This allows you to press the tablet into the dirt and pull the dowel out. The dowel needs to be sanded smooth and sealed to prevent swelling. I used wax. You can use any sealer - just make sure to wipe off all excess. It's a snug fit and too much finish on the wood will cause the dowel to jam.
Step 3: You're Done
To use, press the spike end of the PVC into the soil about 3-4". Drop a pond tablet in the top end. Insert the dowel and press it down. Depending on how snug the fit the dowel is, you may wind up injecting water into the soil. To prevent this you have two options. Leave the dowel in when pressing into the soil -or- what I did - drill a few holes every few inches on the PVC pipe to allow water to flow in and out.