First time growing! Few weeks into flowering! With pics!

This is my first time growing and doing it in DWC. I made some mistakes and the plant is showing them in flowering (the tips are browning and spots are showing on the leaves, but only on the plant on the left, the larger one shows no signs of stress), I had left nutes in the water for about 25days. After reading I am supposed to change the res water/nutes every 10days of flowering.

I build the grow box using pvc piping from Lowes, cost about $25 to build that grow tent. Reflectors are $1 windshield ones from the dollar store.

I am growing with only 2 CFL lights, 42watt each 6500k daylight since I used these lights for veg I didn't want to spend any more money on lights.

Its a 10 Gal, filled with 4 Gallons of RO water, using the Lucas formula.

32ml Micro + 64ml Bloom for 4 gallon.

PH: ~5.8 (Doing my best to keep it at that)
Water Temp: ~75F
TDS:800-900 (Is this good?)

Both plants started from seed the one on the right sprouted ~3 Months ago, and the one on the left sprouted ~2 Months ago.

First signs of female were almost 3 weeks ago, so I guess that means I am week 3 of flowering.

When do they really start to smell, that is the only thing that concerns me?

Hi, just a word of advice, generally vegging only takes 1 month from sprout, the power of your light is not high enough, also when it come to flowering plants need warm light sort of orange colour 2400k, 6400k will not really do your plant any justice in flowering it is perfect for vegging though. The money you saved not buying another light will probably cost you in yield, I'd get a hps 400w on them ASAP