Some spots and crinkly looking leaves?

Not sure what the problem is ,just did a res change and added nutes from SH kit. ppm is about 1200 and ph is about 6.2 The leaves are getting a crinkly kind of look ? and a few spots are appearing . Thanks for any info these are my first hydro grow (ak4 about 20 days from seed.

Hello someone can you tell me if I need more or less nutes ?????