If someone makes their own soil-less mix (and millions of us do), the addition of gypsum is essential to the health of the plants. It's a great way to provide a couple of essential elements without putting the pH out of whack. Not a fan of the Epsom salts in containers. Anyway, your particular potting mix is one that cannot drain well. Those ingredients are fine for in-ground plantings, but not containers. The use of containers changes the entire workings of a soil/root system. Even the finest top soil can begin to act like the enemy within the confines of a container. Since the drainage is going to be poor, you can expect that kind of crystallization to form on the soil surface. If you were to get rid of some of the peat moss, the vermiculite, bone meal, cottonseed meal, Epsom salts, and top soil you'd have something you could work with.

Some kind of mould that indicates the presence of an active fungal colony. White is generally not harmful, although it may be an indication that the soil is too wet since most fungi are not too active in dryer soils.

In a effort to be clear I have rewritten my post about Dr Ingrams. I have used contemporary language to the best of my ability. If there are still questions of what I am saying I will attempt to try again... Im tired of people messing with Dr Elaine R. Ingrams. Dr Ingrams be working hard, real hard. Dr Ingrams got courage and character just like Superman. Dr Ingrams, that girl know about her compost tea (dirt too!), she in the front row (snap) sitting on the corner. Dr Ingrams was telling people to geek up their compost tea. Somebody found out she was doing wrong and put it in the funny papers. You know everybody seen that! Dr Ingrams jumped up and told everybody they were right with the quickness. She covered that butt and dont care what nobody say behind her back. People be talking about they be calling Dr Ingrams all the time. I bet they be calling her when she get off work too, and she talk to them anyway (hmmph). I am NOT having no talking about Dr Elaine R. Ingrams behind her back just so you can stay stuck on stupid. Dr Ingrams is a real nice lady and helps everybody, even if they talk funny to her. Dr Ingrams take them just like they come, she dont pick and choose. If you wants to talk about somebody with me you best be picking somebody else. If not, you can talk to the hand Blutranes

Hi Jayinjay, "Watering from the bottom isn't really an option... I have about 150 plants that just barely fit under the lights. Moving them twice a week to water from the bottom would be too time consuming and I haven't been able to find a plastic bin or tray suitable for holding them, that wouldn't take up too much space where they would still fit under the lights." I think the advantages of watering from the bottom would justify the effort of finding some trays. I have used my PermaNest trays for many years. I have also used some cookie sheets that I got from Walmart as trays. The cookie sheets can act as shallow trays. The cookie sheets add maybe a quarter of an inch of elevation, while the PermaNest trays add maybe a half an inch. It is vastly easier to flood a tray and simultaneously water all the pots in it than to try to water the pots individually. And if your shelf is reasonably level, you can add the water to the tray from the front without moving anything. Good growing mediums will "wick up" the water all the way from the bottom to the top. I use Premier ProMix BX. ZM (not associated with any product or vendor mentioned)