Aqua One Tropical PL18 tube offering a slightly pink, warmer toned light for gently enhancing fish colours. 4 pin fitting. A great soft option the PL18 Tropical Tube from Aqua One offers a slightly pink, warm light that will enhance your fish’s colours and makes for a gentle, easy viewing experience. Especially recommended if seeing your fish at their very best is your top priority. When changing any PL tube take your time and only ever grip the plastic base of the tube. They can become quite stiff to remove so take it slowly and gently wiggling the tube from side to side until it pops out. Make sure the new one is pushed firmly into place. But don’t put any pressure on the glass part or it will shatter.