The tank looks good ukrworld! Not what I'd call heavily planted though. To answer your original question, yes the fishless cycle is stalled. The page for your aquarium says you're using crushed coral? Is some of that in the filter? If so, you shouldn't be having a problem. Adding a small amount to the filter will allow you to finish the fishless cycle. Adding it won't be a problem because it will be removed before the fish are in the tank. What has happened is the bacteria has used up the KH and lowered the PH. Adding the crushed coral will raise though and allow the cycle to complete. The crushed coral can then be removed as the bacteria you have built up won't need to process 4 ppm ammonia daily and thus won't use the KH as they have.