Not after 4 days! Y'all need to read wat he wrote b4 givin yer bad advice!
well maybe you should do some research and maybe some trial and error before you say other peeps are giving out bad advice..
if a clone, gets a yellow leaf, that leaf will NEVER go back to being green again.. if it even starts to get a yellow tint, the older leaf will NEVER be repaired because the plant makes a decision to extract the nutrients from it until the leaf eventually dies off.. it will only focus on the new growth making it green and lush..
so again i say, if it started to go yellow when you first got it, the odds are that the roots were not big enough to extract the proper nutrients from the soil, so it started with the lowest, oldest leaf.. once it started to root, and the mass was great enough to feed the plant, it started using the nutes in the soil to start new growth..
again i say yellowing in the leafs happens from time to time in clones, and if the leaf went yellow, it will never go back.. watch the new growth and it will be fine..
ive been growing for 4 years, and read more books and forums than i care to count.. look through all my posts i dont give bad advice
and a moisture meter? maybe you should be the one not giving bad advice, any reputable grower will tell you that a moisture meter is a piece of crap because not only can there be pockets of moisture in the soil which will skew the readings, but also if you do not test at the same depths you will get different readings..
to know when to water your plant, simply completely saturate the medium, and then wait a few days and start picking it up every day, feel the difference in weight..
wait until you start to see the leaves droop significantly, and get familiar with that weight.. that is when you will want to water your plants... marijuana is a feast and famine plant, which means it does the best when you completely saturate the roots, and let them get near dry.. start to learn your soil and pot size, and try to get them as close to dry as possible before feeding.. weight will tell you the most accurately, dont bother with a moisture meter