I put together a 20L tank this week and covered the background with some black aquarium silicone and peat and the water divider with black silicone and gravel and it has been 2-3 days and neither has cured. I have done peat/moss backgrounds in all my tanks 10 gallons and up and had no problems with this happening before.
I glued the divider in with silicone on Friday and it cured fine but it was All Glass Aquarium brand silicone. The tubes I used on the background were two 10 oz caulking tubes made by some German company - there was only instructions in German and French and a picture of a fishtank on it. I'd gotten the tubes as "bonus" in a box lot of black aquarium silicone caulking tubes off ebay. Most tubes were AGA brand and I have never had issues with it but I thought I'd use these and seems like I made a mistake. Does anyone have experience with European silicone brands? Does it have a odd way of curing other than just room temp vulcanizing? Is it staying tacky because of the heat/humidity going on this week?