It looks like it might just be sunburn or nitrogen burn to me. I'm assuming you've not shown the undersides of the leaves because they look normal? Are you wetting the leaves when you water/fertilise? To be honest, I don't have much experience with diseases on basil, but I used to wet the leaves when I first started gardening and they quickly burned. It looks similar to what I can see in the photo.

Hi Rachel, I agree with previous poster, and would add that watering every 3 days is too frequently for succulents in almost any conditions. Exceptions might be plants in grit (non-soil media akin to cat litter); plants that are very pot-bound, or plants in terra cotta that are in direct sun and high temperatures all day. For a plant in soil like yours, a once-weekly soaking is more than adequate. I agree that a soil change would be helpful. A 1:1 or 2:1 mix of potting soil and perlite will help it to drain and dry out faster, which succulents prefer. A south-facing window is preferable in most climates, but acclimate them First, and don't leave them in direct sun until the roots have had time to colonize the new soil- at least several weeks. Depending on where you live, east or west windows will also work. North-facing windows rarely, if ever, provide enough light for succulents. The smaller plant appears to be a Sedum, burro's tail, I think. On my small screen, it looks like all but the new leaves are a bit shriveled. They should be fat and turgid like grapes. I suspect the roots have died back from too much water/inadequate drainage. When you pull the plants to change the growing medium, examine the roots. They shoukd be white, firm, and profuse. I think you'll find small roots just around the stem, and many of those will be mushy, grey, or shriveled. If they appear that way, it will confirm the over-watering/poor soil hypothesis. Post some photos and someone can let you know if you're unsure. So, new soil, less frequent watering, a pruning or re-start for the Echeveria, plenty of light, and minimal fertilizer shoukd GI e you healthier plants in a couple of months.

Kendra Not the soil to add, but perlite. That is the white granules, few are visible in your soil (but it is better to add more). You can buy a bag of it, screen it and rinse it. I would add some and gently poke the soil closer to the rim with a chopstick (so I won't disturb the roots much), to mix it in - not leaving it on top. Or if the soil in the pot is loose enough, you could shake some out holding the plant. Mix this with perlite and put back in the pot. Perlite is very light and easily floats to the top. This would be temporary help, and if you don't feel confident about doing it - don't. I am only suggesting it for a time until you decide if you want to make 'proper' mix. You would need to make it yourself - they don't sell it in stores. There is just couple of places you could order similar by mail, but I am not willing to pay the $ they ask + shipping so I don't buy it and can't advice you about them. robinswfl gave you good advice, re-read her 2 posts again. Using well draining soil is much better for the plants, and makes it easier for the grower because it decreases chance of overwatering. Sure, even gritty mix could be overwatered, but it would take lots of water to do that+leaving pots sitting in saucer full of water. Keeping plants outdoors is also much better for the plants, and with that kind of soil one doesn't have to worry much about the rain...again, just my opinion.

The container needs a drainage hole - is there any? Try not to handle plants leaves too much, the protective coating is rubbing off. It won't cause plant to die, but it is better (and looks better) with it on. The bottom plant seems to have some mechanical damage - did something fall on it? The 'plump' & soft yellow leaves are sign of water retention, usually. Potting plant that deep inside of container interferes with light access and air flow. It also doesn't look so good, the plant is 'lost'.