Juwel day lite tubes have a kelvin rating of 6500 and create a lovely bright daylight effect in your juwel aquariumr for best results combine one day lite tube with a colour lite or warm lite to give a more natural colouring to your aquarium place the day lite tube at the back to promote plant growth and use the warm lite or colour lite tubes to enhance fish coloursr these tubes are t8 1 thick fluorescent tubes and will fit all juwel aquariums with existing t8 light bars