[GpsFrontier]

Hello Gjn,
Glad you were able to post in the forum.

I'm using it from a 5 gallon bucket.

1. Is 5 gallons your total water volume for the system?
2. What is the water level in the tubes?
3. Is the water running 24/7, or on a timer?

I add Dave's Base Formula (4 TB) and Dave's GROW formula (4 TB) typically every 2 weeks.

1. Do you have a link to the nutrients your using? I'm not familiar with that brand.
2. How often do you do a complete nutrient change?

The mechanics sit next to a furnace so that the water is fairly warm during the day but most likely gets a bit cooler (68?) during the night.

You don't want the water to get much warmer than 68 F. The optimum water temp is between 68 and 75 F. Water temps above 80 begin to cause heat stress.

I would have thought that the basil plants which I transplanted would have doubled in size by now. But they appear to be growing very slow as does the dill.

1. What is the air temps (day and night)?

Their all herbs, but they all have different environmental condition requirements (light, nutrient, temperatures). But looking at the pictures the basil plants are on the ends and not getting close direct light, dill is a lower light requirement plant than basil. led's don't work very well at a distance. Temperatures are likely a factor as well.

So how do I approach this - what is the order of importance:
water temp
light
fertilizer
??

Order of importance:
1. Water temp
1. Light
1. Fertilizer

The chain is only as good as the weakest link. Neglect one of the links, and the chain breaks.

I have two 45 watt LED panels about 18 inches or so above two of the rows.

Would I be better served if I purchased something like the 90 wt BloomBoss (UFO) (Amazon) ?

While 18 inches is within the 2 foot threshold for LED lighting, it's on the far end of that range. There are three main disadvantages to using LED lighting. The high cost of equipment, the drastic light intensity drop off beyond 2 feet, and the watt for watt ratio.

The drastic light intensity drop off beyond 2 feet means that multiple light fixtures are needed. While LED manufactures boast (misrepresent) electricity cost savings using LED because their light fixtures use less wattage, the actual watt to watt ratio needed because of the light intensity drop and multiple lights needed means the actual wattage needed to grow your plants is much higher than LED manufactures lead you to believe. Therefore there is actually very little electrical cost savings if any, that is unless your growing small plants that don't get bigger than 10-12 inches tall. Even then, a LED panel or UFO wont grow many plants because the light drop off beyond 2 feet from the light source means the actual square footage of grow space is very small. Commercial operations using LED grow in rows, and usually use custom designed modular LED tubes or ropes the length of the rows to get even coverage.

(Note) That's using good quality LED's only. With the popularity of LED's on the rise, and thousands of manufactures in china making LED's. Many manufactures are jumping on the bandwagon and producing low quality LED's as well, but selling them at high prices like good quality grow LED's. You can't tell the difference with the naked eye. So unless you have deep pockets, you really need to do your research on the manufacture if you plan to experiment using LED's.