I've been using a variation of subcools Super Soil and never had a def or burn but if you went by the ph of the SS you would be wondering how in the hell the plants havnt burnt but they never do and are always great looking and tasting. They seem to all love it.
Now when I was using FFOF i did have a def that looked similar to yours but worse and after that is when i switched to SS and other than the switch i havnt done anything different. In my case i think is was the FFOF. The base soil im using now is half the cost and a better soil.
I personally dont think your leaves look bad but in any case a flush definetly wont hurt.
BigBudE
Now when I was using FFOF i did have a def that looked similar to yours but worse and after that is when i switched to SS and other than the switch i havnt done anything different. In my case i think is was the FFOF. The base soil im using now is half the cost and a better soil.
I personally dont think your leaves look bad but in any case a flush definetly wont hurt.
BigBudE