I did have one for two years that was 18inch when i got it and it grew to over 4 foot unfortunately i lost that to ich of all things along with my p13 and baby jau couple of months ago. I have 2 more on order but not sure if there just delayed or his having problems importing them.my tank is braced every metre along the top and each gap has plastic sheets then 100mm insulation then taught foil roll and then weighted down but its good to be reminded of the importance of this
