Alejandro..leaves yellow for different reasons. I doubt the cause was Miracid..on the contrary, adding fertilizer, especially Miracid should prevent yellowing. You mention watering once a week..Do you allow soil to dry before adding more water? Watering should NOT be done on a schedule..water when soil is dry..Otherwise, if your soil remains constantly wet, and you add more water, plant will show signs of distress..one being yellow leaves. An 18" pot is pretty large. Is soil well-draining? If your citrus is potted in heavy soil, it'll take longer to dry. I notice you're in NH..too early to take plants out? If they're indoors, overwatering will cause all sorts of problems..including bugs. Especially Fungus Gnats. Every so often problems occur, like yellow leaves..unless your citrus is losing leaves daily, I wouldn't worry. But I think you're watering too much without allowing soil to dry..What do you think? Check the soil before giving a drink..Insert your finger deeply in soil..if it comes out wet/moist, wait a few days and recheck. If it's dry then time to water. Another way is lifting pot..is the pot heavy or light..when light, most likely, soil needs a drink, if heavy, again wait a few days and recheck.. They sell moisture meters, but some people think they're a waste of time. Unless you have two meters, to compare, I tend to agree. The finger and weight test is a sure bet. Check for insects..especially spider mites and scale..look for webbing..do leaves feel sticky? Check for brown or white lumpy bumps that can be scraped off.. I wish I could help w/pics, but I've no idea..maybe someone else will chime in..Toni

Here are three pictures from this afternoon. The small leaf in the container must be a newly dropped one some time today. I am in central WI. Our weather this week looks to range from 82F-88F with majority of days on the lower end. The lows are in the mid 60s. I will note that I do not think the tree has grown. At least there appears to be no new buds. I've had it for just over 3 weeks now. Note: I removed the stake once and the tree was angled about 45 degrees when I went out to look at it one day. I have it re-staked and tied near the very bottom now. This post was edited by Neurosci on Fri, Jul 5, 13 at 19:48

I have washed my tree, it took awhile :) Now i'm bringing it outside for a few sunny hours a day and hope that the leaves will start looking better soon! I took off whatever was in my trunk, it was like a light colored jelly covered by dirt..washed it and gently scraped the rest off with a shape knife. Does anyone know what that is? Irina

I'm not seeing any sign of scale. A month or so ago it had a few aphids and accompanying ants, but they've been gone for a while. Interestingly, I was at a garden center today and saw that several of their Meyer lemon trees had the same thing going on. It was not the place where I bought mine, but the grower was the same. I asked the guy working if he had any idea what it was, but he was no help. Could it be fungal? I never water the leaves, but as I said, August was cool and foggy, and fungi of all kinds love the climate here.