If by small holes you mean pin-point size and lots of them...a nutrient deficiency. Interestingly I have this now in my 90g, brought about I believe by an excess of magnesium [won't get into all that]. I would recommend a basic comprehensive fertilizer.
With respect to Nutrafin Plant-Gro, I have not used the liquid form. I do use the sticks and they are incredible. However, I also use Seachem's Flourish Comprehensive Supplement for the Planted Aquarium
which allegedly contains all essential micro- and macro-nutrients in roughly the necessary balance, so any specific nutrient deficiency in the sticks would likely not be of effect.
Nutrafin liquid does not contain all the nutrients that are in Flourish. Here are the specs on Nutrafin: Nutrafin Plant Gro Aquatic Plant Essential Micro-Nutrients - Live Plant Care - Fish - PetSmart
and here are Seachem's for Flourish to compare: Seachem. Flourish
You will note that "potassium" is not listed in either. I have been using only Flourish for more than a year, with great results. However, if in both our cases potassium is the deficient nutrient, neither of us will be getting it with either product. Dosing with single nutrients is something I never recommend because the nutrient needs of plants is proportional and an excess of some can result in a deficiency of others when the plant "shuts down" assimilation of other nutrients due to the excess nutrient. Potassium excess has been shown to result in iron deficiency in some cases. But increasing the iron is dangerous because iron is a heavy metal and thus toxic at excessive levels, and years ago I actually killed off some plants by using iron on its own [another reason I don't recommend individual nutrients], and in any case, if the plant is not assimilating iron due to the potassium, increasing iron would be useless.
It just so happens that last week I began a new product only available in the Vancouver area so far, manufactured by an aquarist on Vancouver Island. It has a different combination of nutrients, and includes potassium, and others who have used this in planted aquaria for more than a year highly recommend it. I will be interested in seeing its effects. In your case, I would suggest either Flourish or Kent Freshwater. I used the latter for more than 10 years and I had no plant problems whatever, any my water is very soft with no mineral in it, so the Kent must have covered the basics.