Thank you for your input. The humidity varies between 50 to 60 percent relative. I don't have a very accurate ph meter. I am using a moisture/light/ph meter I got from Home Depot, which, if I remember correctly, cost about $10. I would like to get more accurate equipement but simply cannot afford it.
I will flush with pure water - as pure as tap water gets, that is. I don't have any distilled. And before you ask, yes, I do let it sit to de-chlorinate for at least 24 hours prior to use.
Do you have any idea what species this could be, that it is so different in size, shape, and growth?