I suppose it's
possible that your problems were caused by the otos, but personally I don't think it's very likely. The leaves in the first photo (especially in the circle in the top right) look like they're crinkled -- almost like they've been folded. I've seen similar things in some of my plants,
also right after starting dry ferts (phosphate, actually). At first, I was dosing everything but phosphates (which I kept at or very near 0 ppm with phosphate removing filter media). In my experience, PO4 'deficiency' seems to not have much effect other than slowing down growth. My plants were not growing extremely fast, but the leaves looked normal. A couple months later I decided that I should see how they grew with PO4 being added (and the PO4 remover taken out). The plants REALLY took off, but that's exactly when I started having problems with crinkled and deformed leaves. I think when the plants were PO4 limited they were able to get enough of the other nutrients they needed to have normal (but slower) growth, and could not do that fast enough when PO4 was no longer limiting. I'm actually still trying to figure out exactly what (calcium?, some trace element? an excess of a trace element?) it is that's causing it though.
Here's a picture of my Ludwigia that I took some time ago, when it was happening the worst. This was definitely not the worst of the crinkling though. Some of my vals were putting out leaves that look like somebody had folded them like this: /\/\/\/\/\
I'm not saying that that is for sure what happened with yours -- but just out of curiosity, I have a couple questions. Do you know what your GH and KH are? Calcium levels? Were you dosing PO4 at all before, and did you happen to test for PO4
before you switched to the dry ferts?