I have been feeding mine tomatoes probably 2x a week for the last 4 weeks, but I use it as a fruit, because it seems like the month of October has been "fruit strike" month. Seriously, they seemed to have all posted a ban on fruit. I don't feel too bad about the calcium though, because they eat lots and lots of leafy greens, like collards and spinach (some every night); yes, there is the acidity issue, BUT...that is why I feed it as a fruit. Tomatoes are more acidic than most vegetables, BUT it is actually LESS acidic than many fruits (believe it or not...it's true..you can look it up), such as pears, peaches, plums and strawberries. The least acidic is (I think) the yellow pear shaped cherry tomatoes. Fortunately, mine like beets also and they are somewhere in the PH 6 range; the only other things they will eat currently fruit-related are cantaloupe and papaya..so frustrating. However, all of these, YES..including tomatoes, are middle of the road...neither truly acidic nor alkalizing.
Just to dispel a myth, many citrus fruits (for example..lemons!!) are actually alkalizing and are probably not so bad too feed; even though they are acidic ph level; they have the opposite effect in our bodies and are alkalizing in the blood stream...since gliders are mammals with blood, I would assume the same is true, but I really haven't tried since they didn't like oranges the one time I tried anyway.