Hydroponic Lettuce plants just showing growth at day 4

Here i have my hydroponic lettuce plants, I have about 80 heads of lettuce. I had a few baby plant die off before making it to planting time. This was due to our seed depth in the foam blocks. I think we must have put them too deep or they shifted when we waters them and for some reason they died i think from root and they were too deep in the foam block to come out the top , I cut away foam from many of them and so saved a bunch, But we ended up without enough lettuce plant and some of them are also very damaged due to the foam depth issue of the seeds. So next time we will be careful to wet the foam blocks throughly before planting them. Also we will make sure to not put the seeds to deep in the foam block. But once we put the baby plants into the foam blocks the began to grow and WOW the roots started growing. Little changed on top for the first few days. In the empty spots i have tried to find other plants and some are surviving good and others maybe not. See the baby lettuce coming out of the plastic tubes, I used 2.5 inch pvc tubes and drilled them to fit my little net cups. I put them about 15 cm apart for each lettuce plant. I used a door hole drill bit kit with multi sizes as to fit the net cut. I dont know maybe it is about 2 inch? size.