What are these symptoms caused by?

[baimoo]

2 of 3 plants all in the same room are looking very sickly. The two sick plants are droopy and are a much lighter green than the healthy one. As well, the tips of the leaves are turning brown and curling up, and eventually dieing. Also, there are a few brown spots on the leaves. Can someone tell me what this sounds like. I figure since one of the plants isn't having these problems at all that it would eliminate some possibilities. Any help would be appreciated.

They are all in soil, under fluorescent lights. I fertilize them every two weeks. I was giving them 20-20-20, but now I am giving them 10-15-10.

 

[bigbudsbruddah]

I have a few questions before i can answer.

How often do you water it?

What ferts do you use?

What is your setup( Lights, Soil, etc)

 

[baimoo]

I water them every few days. I have them under two 4 foot fluorescent lights (2 x 34 watt bulbs per light, so 136 watts total for three plants). I am using Sunshine Mix #4 and every two weeks I fertilize them, with the most recent times using 20-20-20, and then 10-15-10. Is that enough info?

 

[bigbudsbruddah]

You may be nute burning them. Try flushing one of the plants and see if that helps. Also what is PH of your water you are giving it.

 

[Growdude]

I water them every few days. I have them under two 4 foot fluorescent lights (2 x 34 watt bulbs per light, so 136 watts total for three plants). I am using Sunshine Mix #4 and every two weeks I fertilize them, with the most recent times using 20-20-20, and then 10-15-10. Is that enough info?

How big are they now? those are powerful ferts.

 

[baimoo]

How big are they now? those are powerful ferts.

They are 3 feet tall. I was giving them 20-20-20 on the advice of someone at a hydroponics shop in an effort to reverse the plants from flowering. That was successful which is why I switched them back down to 10-15-10. But still I gave all three of them the same stuff and one of them is doing great while the other ones are doing terrible...I don't understand why. I tested my tap water ph today, it was 7.2, I know that's a little bit high, but the bottled water that I bought turned out to be lower than 6 so I opted to stick with my tap water. I am going to try flushing one of them, and then I will post here again with my results.