I am not sure what kind of cactus you have, but I don't know of any that would like that kind of pot and those conditions. Those pots are meant for African Violets and other things that like constant moisture. Cactus don't! I would transplant and then follow the direction on the cactus foood. I use the Schultz stuff but I hardly ever fertilize and they are fine without. Most don't require a lot of food. If you are going to keep it in that pot to see if it will survive, I guess you could put the fertilizer solution in the pot every 3-4 months and let it leach in like the reg. water does. A lot of the nutrients may get trapped in the ceramic though. Another options would be to get those house plant fert. sticks, cut them in thirds and put 1/3 in every 3-4 months. That way your not pouring water into it that can't get out. I still think your plant won't survive long in a pot like this.

I would agree with the above reply. Most cacti prefer to dry completely out between waterings and during the winter most like to be very dry. I think that sooner or later you would run into problems if it remained in that pot.

I'll "third" that; this is not a good pot for a succie.

Don't let the cactus pot sit in water. Have you heard of liq. fertilizers, about 1 tbs per gal of water, don't let it's pot sit in water once it takes up the water that it needs remove the rest of the water in the tray (saucer). This will not take more than an hour, depending on the size of the pot. Let it dry out between, take a chop stick and put it into the soil, and see if it needs water.
Group please edit if I didn't make sense. Norma

So, Norma, your saying it's okay to use the pot but only put water in it when it needs the water and only let it drink for about an hour at a time and then dump the rest of the water out? It makes sense, but then why use that kind of pot at all? Buy and AV for that pot and get an inexpensive clay pot for the cactus. It will be happier, IMO.

I wouldn't use the self-watering pot at all. It is not designed to completely wet the soil in a short period and then let it dry out. You can grow in almost anything, even a pot with no holes in, but if you don't water a cactus the "standard" way you will almost certainly kill it within a year or two.

I think Norma thought the poster was talking about one of those plastic self-watering pots, where you pour water in the saucer. Just a guess?
I think what the poster is talking about is an inner pot made of very thin clay that absorbs water from the outer pot that it sits in.

Gabi

And by the way, I definitely would NOT use any type of self watering pots on any succulent.

Gabi

Please get it out of that pot ASAP. Cacti don't like to be drowned.