Need help with macro grow bloom use in hydro

[BetrayedSoul]

A beginner needs help with feeding in hydro using macro grow and bloom.
This is post he asked in

First Tim Grower BIG PROBLEMS. HELP PLEASE

Hello this is my first time growing. I have a 3 foot by 2 and 1/2 foot grow cabinet. I tried growing some watermelon zkittlez seeds. They germinated well for the first two weeks 3 weeks and then I started seeing a decline. I have a dwc setup. They all died on me 4 plants all together. Can somebody please help me I’m asking please I don’t want to ruin my new hobby .can somebody please help me with this or what am I doing wrong??

Please help before the plants get nuked !!!

Thanks in advance