I assume your in soil, but it depends on whats in the soil and how long they are in there. If you want to try for the best harvest you can have, I would say yes you do have to feed them. They inside ? Outside ? Since you mention sun I am guessing your outside.
Ya, the 'P' would be my guess too by the way the patches look on the leaves. I've never tried coco but it sounds like it's staying wet to long and they don't get enough oxygen to the roots. Why were you flushing ?
I don't know if it could be a fungus. It's good to keep at least some fans on while the lights are out to maintain good air flow around your plants. I don't remember if the Dolomite is the fast acting lime or not, you could google to find out. If your water is distilled or very soft it will help...
Sandman, depending on what you are using for water (if it starts out with a low PPM which would mean its soft water) you might try some CalMag for the spots. If your soil isn't draining you need to change it for the next run and just hope for the best for now. You NEED to use a soil that drains...
Looks like P deficiency in part (the light spots in the middle of the leaves) But looks like more issues than that. Maybe some under watering or over water too. You been fertilizing ? Check the guide I posted above, it has good pics to help find your problems.
I was having a problem when I was doing hydro but it was the PH going up really quick, I blamed it on the temp being to high. Some nutes like Canna have something in them to help keep the PH in check. What kind of nutes do you use ?
Hey stoneguy, I can't say off the top of my head buy do a Google search on it. There are household items that you can use to raise and lower your PH. Like baking soda, vinegar etc.
Have you looked through this:http://www.icmag.com/ic/showthread.php?t=11688
How do you know it's not from genetics ? Sometimes they'll do what you don't expect.
Hey polarbear, the miracle gro has time release nutes in it and flushing it might not really work and could make it worse by disolving more of those into the soil. I would get rid of the Jobes spikes like you did. Pics always help when you can so we can see them for ourselfs. But from what you...
Hey BlueB, looks a bit like light bleaching to me but I couldn't say for sure. What do you have for lights and how close are they ? Here is a link to a really good problem guide, it seems to cover most anything.
http://www.icmag.com/ic/showthread.php?t=11688