Hi guys. For the first time since I've begun trying (about 7-8 months)I am having some success growing tomatoes indoors. I have 2 400 Watt Metal Halide lights setup in a 4x4 space.

I am growing in Sunshine Mix#1. I have added an additional 20% perlite to this mix. I have also added a small amount of worm castings and dolomite lime to help with maintaining steady pH.

I have constant air movement going on in the setup and the pots dry out quite nicely, usually every 3-4 days. This is the first time I feel like I can water all the way through until runoff, yet still have the pots dry out in a reasonable amount of time.

I am using tap water mixed with rain/snow water or RO water to get my starting water EC to about 0.2. The nutrient line I am using is Pure Blend Pro (Grow, Bloom), Liquid Karma, Cal Mag Plus, and Earth Juice Microblast.

Early on I got the seedlings going by using a feed, plain water, feed, plain water cycle. Occasionally I would go two plain water irrigations if it looked like feeding may have an adverse effect.

I start with water at 0.2 EC. Add Earth Juice Microblast (a micronutrient supplement) until EC reaches 0.3. Liquid Karma until the EC reaches 0.4. The Pure Blend Grow Formula until EC reaches 1.0-1.2. I kept this basic formula up reaching a maximum of 1.7-1.8 EC as the plants grew and began flowering.

I am now tending two 4 foot tall chery tomato plants in five gallon buckets. I could not tell wheter the tomatoes where progressing as quickly as they should have been. I thought I may have been undefeeding, and I sort of toned down the feeding just a bit,as I experienced some slight tip burn (darkening). But I abandoned the alternating feed, water cycle and just fed. I also got some slow black/brown necrotic spots appearing on the lower portions of the plant. Also, some unpruned lower sucker branches have shown blackening/browning on the growing tip. The problem seems to be slowly working its way up the plant. But is not present on that many leaves. I figured with tomatoes purportedly being heavy feeders I may have been underfeeding, and maybe they began eating themselves so to speak. The least watering I upped the feed to about 2.05-2.1 EC (with about 0.3-0.4 made up of Pure Blend Pro Bloom. The rest as usual with Liquid Karma, PBP Grow etc)

My basic questions are this: Should I be using the feed, water cycle to prevent nutrient buildup even at this advanced stage of growth?

Secondly, What should my feed strength be at this stage? Each plant has about 3-4 branches with good sized tomatoes on them, plus at least 8-10 flower clusters waiting to set.

Thank you very much for any insight you all may be able to help me with.

BP