You mean the drooping leaves?

It doesn't look THAT bad.

Just looks like maybe some overwatering. Only water when the soil is dry, and don't water so much that the soil is mucky.

I'm guessing the real problem is the HPS you added.

Are you in flowering or vegging? Sorry if I missed that part.

If you're in vegging, the HPS is not a good idea to use. It is not the correct light spec. for vegging.

But if you're flowering, get that HSP back in there. Cannabis love HPS for flowering as they are the closest to sunlight in light specs.

If you're in flowering and you added the Hps, and leaves started sagging, all it is, is the plant going through some light stress, getting used to the change. It is very common, so don't fret.

Your plant will get over the slight shock in a few days, but if youre flowering, get the HPS back in there, if not, keep the CFL's until you're done vegging, then add the HPS for flowering.