Now what Im about to say is from experience so please dont throw any "overwatering" issues my way. NEVER let the coco dry out. Water at least everyday for seedlings (once a day then when they are bigger you can increase frequency for faster growth). I used to let the coco dry out when I fed seedlings and ran into stunting and what looked like nutrient deficiencies (when you let coco dry out, when using nutrients, the nutrients get concentrated to a high amount that it either causes a nutrient lockout or worse nutrient burn) but Ive never run into issues of fungus (anything close to dampening off) so this advice might not help you. I just saw that what looked like coco was dry and I wanted to share this with you. When you put coco in solo cups like that it tends to starve the seedling from oxygen thus feeding every day puts new oxygen via water and gravity itself pulling in oxygen from the grow area. Im sure this will help you out if you care to try it. Also now that it makes sense lack of of oxygen and a wet environment is what can cause dampening off. Hope this helps you.