lighting i need extra lighting could i use a tube light

could i use a tube light to put extra light under my plants there 6 weeks in to bud n there in a small room i was planning to just get 2 of my clones to root but all three rooted so i couldnt bin the little baby away even tho my grow room was two small its 150cm by 100 ncm n 7 foot high the light doesnt reach the bottom of plant very well i have a tube light u know like the ones from a fish tank the uv ones could i place this under the plants 2 give the bottom buds some extra light and would it help any i just dont have the funds 2 buy anther light to add under my plant as my first attempt died due 2 heat r lack of magnesium not sure witch one but these r doing fine plz could some 1 advise tnks
 
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