hi guys! so i have a 15L biorb and am having trouble with the bubbles! every time i have to switch my filter off to do a water change etc , once it’s turned back on the bubbles are jolty, weird sounds , weak or non existent. i’ve tried the blow down the tube and bubbles come out (i have to blow hard but a lot do come out) so i don’t think it’s this. my tube has water droplets but very few and i don’t think this is a problem. i took apart my air pump and found a small amount of water in the rubber bit and cleaned this out and put back together . bubbles now are coming out, a few strange noises though. i’m sure many of you understand that u know when ur fish tank just doesn’t quite sound right! at this moment it sounds fine but i doubt this will last after my next water change... any tips? has anyone else experienced this ? ps. the air stone has just been replaced and so has the filter foam pad.