Seedlings keep stretching with Spider farmer sf-1000

Place them in bigger and you'll be good. Light setting is good imo. Seedlings tend to act this way since roots detect they have no more space. Give them bigger boots and wait for 3 days and you will see they stop growing upwards but rather new pair of leaves starts forming and seedling grows into plant. Lower the light to 50cm when you do that and increase air flow. 50% RH should be enough with 27 degrees celsius at least

Recommendations are fine, but in the face of reality, you must react to reality. The ones stretching need more light. It is not the brand of your light that matters, here. Simply give those seedlings that exhibit stretching more light. if some are not stretching, you will need to provide 2 different levels of light... distance from light, offcenter the ones that need less, a shade to attenuate intensity for some, etc.. there is more than one way to accomplish this task. Once they sprout, you don't need a humidity dome unless your climate is very dry, so you can split them up and provide variable amounts of light to specific plants as needed. A healthy vpd for young plants is fine (find and download a VPD table). Get a humidifier for the room if you live in a desert.

Remove the RH dome. and include some air movement. don't point it at the plant point at a wall or corner and let it just breath. The Dome is taking some of the lights intensity away. Running the light higher like 100% at a greater height eg 30" will give a better overall lightmap vs 15" at 50% 1/2 its setting before.

It shouldn't still be under the dome. As soon as you see green cotyledons, they need oxygen and CO2, not 80+ RH. at 75-80rh, stomata close entirely to prevent drowning in the air moisture, the entire premise of high humidity during germination is to keep the moisture consistently high enough to give the seed time to break out the shell without drying out, other than that you do not need high RH for a seedling so long as you keep her supplied with water at the rootzones and your not running extreme condtions she will be fine. 0.04% of the air is CO2, let us not raise RH to 75 %+ and lower that precious, vital 0.04% CO2 to 0.0001%. The plant needs to perform gas exchange before it can photosynthesize. Akin to strangling someone to death, cutting off their air supply, then wondering why they keep stretching to get outta hell. Gluck.

Put them in bigger pots allow the roots to grow riattaccato will be fine