Only got green Gelato and royal medic going out of...

Whith a 7ph in coco the weaker are dying first then the others will follow. The good ph is 5.8 for the sweet spot in coco

It looks like a classic case of a condition called "Damping - Off". https://www.dinafem.org/en/blog/damping-off-fungi-cannabis-cultivation/ This basically is a fungal disease which attacks seedlings caused by having an overly wet substrate and or excess humidity. Even the most experienced growers still have the bad habit of over watering on occasion it's something about a fear that small seedlings and plants will dry out too much before you can catch it. I personally have found that many seedling and soil mixes hold way too much moisture. Adding in more perlite and drilling extra holes on the bottom of your pots or using air pots,fabric pots help your substrate dry more evenly. After the first 10 start days start to establish a wet then dry watering cycle is good and forces the roots to grow deeper in your pots in search of moisture. Obviously not to the point that the plant wilts of course. I also suggest when using a seedling or soil mix to moisten the mix in a bucket then mix by hand or with a sterile mixing tool just for your grows don't use tools and equipment from your yard it could be contaminated. When mixing you will add only enough moisture to hold your soil mix together when squeeze in your hand yet it will easily crumble when touched. It should not be muddy or dripping water when squeezed in your hand. Adding dry soil to a pot then watering it in is the worst way to start seeds and small plants. The root system get starve for oxygen and is unable to absorb nutrient properly. Maintaining a 70% humidity level is best to slow down evaporation try using a cool mist humidifier in your grow space is best or you can use some clear plastic solo cups temporarily with a half dozen 1/2 inch holes to allow for air circulation. Check out my current Blackberry/ Lemon AK-47 grow I have a few photos of this. I have also found using a store bought turkey baster is ideal for watering seedling and small plants it allows you more control in how much water each receives. If your still having trouble trying to determine moisture levels they sell digital moisture meters that will help you see how much moisture is in your containers at different depths.(Don't tell any one but I use one all the time) Lastly unless your soil has some nutrients the seedlings don't need any nutrients until day 10. Then I would start at 1/8 to 1/4 strength nutrients. Hope this helps stuff like this does happen when growing.👍

If your seedlings are sick and you’re still investigating the problem, move your grow light up and don’t attempt to train your plants or do anything new until they’re better! If you avoid stressing them out any further, they often recover much more quickly. If you notice your plant is droopy all the time, even in the mornings, it almost always means there’s something going on at the roots. It might be getting too much or too little water at a time, possibly watering too often or infrequently, or its roots could be sick/damaged. The other major cause of drooping and wilting is high temperatures. You have been overwatering seedlings like liggt damp moist soil. Not soaked. Possible Triggers For Root Problems Heat – cannabis is more likely to have root problems at higher temperatures Cold – cold roots are unhappy roots – cold shock can cause wilting and other problems Over-watering potted plants – too much watering tends to cause root problems No drainage hole at the bottom of the container – if water can’t get out and water is sitting at the bottom of the pot, the roots can “drown” Muddy or thick soil – if your soil is muddy and thick instead of rich and fluffy, it may mean the soil doesn’t hold enough oxygen to support your roots. Small plant in a big container – When a seedling (or small plant) is in a big container, it often has trouble getting enough oxygen at the roots. Until the plant has grown bigger and started to fill up the container, it’s important to avoid overwatering. It can help to water just a little bit at a time, in a circle around the seedling, until it starts growing faster. Plant has “overgrown” it’s container (become rootbound) – The roots of a rootbound plant have started circling the outside of the container, causing watering and nutrient problems even if you’re doing everything right. When this happens, you may need to transplant to a bigger container to stop the plant from being “choked” by the roots. Big plant in a small container – any time you have a big plant in a small container, even if the plant isn’t root bound, you increase the chance of underwatering since the plant quickly drinks up all the water in the soil! Certain strains are more prone to root problems than others, but good root practices will allow every plant to thrive