Lighting Question.....

[mattlee]

I have 2 small 40L tanks side by side for fry and shrimps/snails they are ex shop tanks with drilled holes in the rear so i can only fill with 30L of water, i have then length ways on to save space. my question is if i hung a light above the 2 tanks to light them both what power light would i need? i have an arcadia starter thats 25-30Watts but no tube that works at the minute. the removed tube was a 20W so can i use a lower wattage tube on this starter safely? or do i need to use a 25-30Watt tube?
alternativly i could get a lower wattage starter and lower wattage tube (if so recomendations please), it doesnt need to be anything fancy as its a breeding set up in the garage but just want enough light to get the shrimps etc out of darkness since the tube has packed in.......

 

[three-fingers]

A good guide would just to be go for something that spans the length of the tanks.

I like to over-light my fry tanks so I can get lots of algae and easy plants growth, making the water naturally perfect for them and providing food. Light powers ecosystems (well, most of them).

More light = more algae = more snails, copepods and other critters to feed baby fish.

But if you just want them to look nice and grow a few plants, just one florescent tube the same or just under the length of the tank will still be more than enough.

Yes, you should be able to put a lower wattage tube in the starter. Worst case scenario, from what I understand, is that the tube could be "over driven" making it's life shorter and the light a bit more intense. But I'm not sure that will happen. I think it depends on the ballast. It gets done at my work all the time when it's not worth opening a new ballast for something and we need to light a small tank.