First of al clones don’t like a wet medium,a moist medium works best..once they start rooting you want those roots to go and searching for water
so if your medium is wet they have enough moist so they don’t grow as fast
Second thing is your light spectrum,clones do best under low output lights like A tl865 or tl845..your hps is way to hot and the wrong color spec and it makes the clone wanna transpire but she has no roots to suck up moist
Third point..humidity:try and keep it above 85 with fresh clones,they don’t have any roots so they absorb moist tru the stomata,if humidity is to low there is nothing she can absorb so she wil slowly starts drooping
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