Thank you. I'm in Toronto. Whatever zone it is...Although I have a huge window not much light comes through so I keep the lights on all day long . I use day light bulb(Philips, 42w=150w)$18.00, I bought at Home depot and they also have a nice lamps which I use as grow lights. They sell them for about $25 or something... So far I have 2 calamansi, 5 nagami and 1 meiwa kumquats, bearss lime, ponkan tangerine, meyer lemon, variegated pink lemon and my beloved kaffir lime..Hope it warms up soon so I can move them outside...

I agree, with Benny. I NEVER use a moisture meter, I think they cause a lot of trouble. I rather prefer to determine the water content of containers by two methods, 1). weight of the container and 2). The use of my finger. After you have had a tree for some time you get to know whats going on both above the soil line and below. Till, the reason people are recomending a smaller container is because you stated that you "soil" has remained wet for over 3 weeks. Except for the top inch or two of the "soil" in a container, which can lose moisture from evaporation to the air, the primary, and almost only way moisture is ever removed from the rest of the container is through root absorption by the tree. If your container is still wet after 3 weeks (if additional irrigation has not been given) then that demostrates that the size of the root ball to the size of the container is out of balance. Especially at this time of the year. I think your trying to hard to figure out the meaning of the word "draining" as it is related to a container medium. It means that the medium when irrigated can hold a substancial amount of water while not losing its ability to also hold a substantial amount of air. The over flow drains off quickly instead of remaining to waterlog the potting mix, as happens in highly dense mediums. The volume of air space in a container should never be below approximately 25% of the containers volume. I like 30 - 35 percent. For recomendations on lighting type the word "lighting" or something close into the search function in this forum. Millet

I tried bringing the plant outside a few times but it seemed to suffer a little since temperatures go from 47-90 within the same day, and so I brought it in, but I could put it back out if that would be better for it. The plant gets about 5-7 hours of direct sunlight (its by a southwest facing window) and I haven't fertilized it since I've had it such a short amount of time and the nursery put slow release fertilizer in it. I keep the pot elevated and empty the drip tray if there's any water in it to make sure it doesn't rot from sitting in water.

I think it may be underwatered even though it’s indoors for winter. Mixes that drain extremely fast like that normally don’t have enough time to absorb water. Tapla has an old discussion about water retention and something like 50% moisture content contained by the media is the limit for how dry you can let it go without damaging your tree. After that the roots have a very hard time trying to take water from the media. Imo, I wouldn’t let my pots dry that far down the bottom unless you recently repotted it and know there aren't any roots down there. The mites are probably from the dry conditions of your tree. Spider mites like dry environments and your heater probably ensures that’s there’s no humidity. Your tree is also less active since it’s winter and paired with little watering, it’s probably not transpiring enough of it’s own moisture to keep it humid enough either. I’m not sure what would be the best resolution since your trees can’t be moved anywhere else at all. It might help to keep it further away from the heater though