Spinach seems to get yellow on the edge which seems to spread to the whole leaf then drying up.

I have built this hydroponic setup and have planted spinach and fenugreek. Fenugreek seems to grow well on the other side Spinach seems to get yellow on the edge which seems to spread to the whole leaf then drying up.
Culprits that I think are:
1. High temperature: the temperature i. The setup shotup to 36 Celsius.
Fix: added cooling system
2. More Nutrients: i might have added more nutrients solutions? The solution A and B ones?
I am not sure how much to add because I have started this just a month ago.

The solution ph is 6
The light intensity on the plants: 150-200 micro mol/sq.m/second

Any help if you have faced this issue would be great learning for me!!
Thanks in advance and please find the pics below for reference!!🙇‍♂️