splitting Swiss chard leaves question

I'm growing ruby red swiss chard (the plants are a few inches tall) and I noticed that the leaves are sort of splitting in the middle, like the leaves are literrally sort of ripping in half in some areas.  Another one has these dark unidentified spots on them that I don't understand. I'm growing them in a long rectangular container with sand, earthworm castings, mushroom compost, top soil, peat moss, perlite, and leaf mulch. I had previously harvested some french breakfast radishes a month ago from the container before transplanting the chard into them. Didn't fertilize the chard until a few days ago though (I fertilize with earthworm castings, I don't know how much I should apply but i usually just give it a heavy sprinkle and water it in, I hear you don't have to use very much but if you do it won't hurt the plants). I feel like theres something that theyre lacking, even though other than that they look pretty healthy.. anyone experienced this before?

I'm in zone 8/9 by the way

i have chard plants that are almost 2 years old now. usually when it gets hot or dry some of the leaves do that. but id say 90% of the time they are healthy. i feed them castings by the handful every few weeks as a top dressing and aerated castings tea for foliar applications.

I'm also zone 8/9, N FL,  and I've grown 4 cultivars of chard.  I know nothing about the split leaves.  If removed, does the next set of leaves also split?  The County Extension may be able to offer an answer here.

The small spots sound like a bacterial leaf spot.  It would be practical to remove the spotted leaves. 

thanks for the advice, as for the leaf splitting I think its just one of the plants that is doing it. The only problem with it (and the bacterial leaf spotted one) is that most or all of their leaves are doing this, and these plants only have about 4 or 5 leaves in total so I don't know how many leaves I should remove without hindering it's growth.

I've had swiss chard and silverbeet split like you described when over watered, i just remove split leaves and cut back on water,( i am in tropics)

how big/old are the plants? if there young enough it might just be worth it to replace those with new healthy seedlings.

I'd hate to see them replaced.  They are about to produce seed.

They're probably around two months old, I seeded them indoors in late October. Transplanted them out in early December. There are 6 seedlings in total. I could probably just try to cut back on water( the biggest seedling is the one with the splitting leaves), and potentially remove the bacteria spotted one to not spread to the others. Their are a couple random seedlings also popping up in the container so the ones lost would be replaced over time..

I just looked at the chard and (not sure how I didn't notice this) they all have little dark spots, and leaf splitting. ayiyi. The situation thickens

well when i said replace, i meant eat mostly. and sprout more of course. also it was said they only have 4 leaves, so i assumed they were just seedlings. the ones with splitting i wouldn't worry about, when we get those leaves we just cook with them, you cant notice. but if your 100% sure the others have a bacterial problem. it might be best to think about what they are really worth. chard is an easy plant to sprout and seeds are dirt cheap.

I removed all of the spotted leaves and the plants are no longer showing them. Simple as that I guess. I will keep posting about it though. Still waiting for more leaf splittage but so far so good.