with photobucket it is very easy. Just mouse over (put your cursor on) the individual photo. A little square will show up with codes. Just click on the bottom one, the IMG code, which copies it. Then paste it in here (you don't have to use our Img button, that coding is already in what they give you).
It sounded like you were talking about hydroponics, but the picture above is just a couple of (yes very unhealthy) tomato seedlings in a plastic cup sitting on a stove. Did you pull it out of the hydro system for the picture? I know next to nothing about hydro, but I don't believe they would ever have things in cups in the system.
A picture of the system, not just the cups on the stove, might help, since I am having trouble understanding it and understanding what is hydro about it... a lined tupperware with humidity dome.
If aphids were causing that much damage, I think you would be very aware of their presence. I think this is an issue of conditions, water, nutrients, light. You mentioned the coco coir, you didn't mention any nutrients. Coco coir like peat is a sterile, nutrient free growing medium. Plants can't survive without nutrients. Also it sounds like you have plenty of light, but it is outside the humidity dome, which probably filters it. And I don't know about the water issues, since I don't understand what you are doing and what the hydro part of this is. Personally I think humidity domes are only for germinating seeds and are very bad for seedlings to stay under them.
Location the moon, is very cutesy, but doesn't give us any information. If you are anywhere except the latest season areas, I think I would give up on the starting tomatoes from seeds for this year and go buy yourself some well started transplants. Your seedlings look terrible and are not likely to do much in time for this season. We all learn from experience and there is a lot to learn about indoor seed starting, especially if you are trying to do it hydro, which is technique heavy.
I'm in Ohio and my tomatoes have been in the ground for a month and have little tomatoes on them.