If it is indeed a deficiency dosing ferts will definately help and hopefully solve your problem.
The damaged leaves will need trimming unfortunately they wont recover.
Dosing ferts is always a good idea even in low techs with "easy" plants such as Java ferns mosses crypts and anubias.
I dose micros macros and easycarb.
I also make my own ferts with dry salts which is the most cost effective and effective way of dosing imo because you have full control of what going in your water.
Micros (Trace Elements) Is what you want. Its basic plant food that contains the basic ingredients plants need to thrive.
I use this...
http
/www.aquariumplantfood.co.uk/fertilisers/chelated-trace.html
Its basically a brown powder. For £5 you get 250g which will last months if not a year. Not bad for a fiver huh?
Basically all you do is add to distilled water as follows
2tsp (approx 12g) of APF Trace Elements to 500 ml of boiled and cooled water. Leave to dissolve overnight.
Dose 5ml per 50ltr. of aquarium water per day
Thats it
Macros is Nitrates Phosphates Potassium and Magnesium. Your set up does not require macros right now.
Macro dosing is only needed when injecting CO2 OR dosing Easycarb.
Reason being is that plants grow alot quicker and absorb alot of these key nutrients quicker when being dosed a carbon source.
Here is a link to a macro and micro kit
http
/www.aquariumplantfood.co.uk/fertilisers/ei-starter-kit.html
It will come with full instructions on mixing and dosing
This will also last for months on end
Easycarb or Florish Excel is like a liquid co2 alternative.
Not always 100% nessersary but it will do wonders for your plants.
They will grow faster and healthier than youve ever seen. Dose this daily and with the right flow you can completley out compete algae.
My tank has no algae at all!
Remember tho if you dose liquid carbon you must dose macros.
http
/www.ebay.co.uk/itm/Easy-Life-EasyCarbo-CO2-Carbon-Plant-Fertiliser-for-Aquarium-Fish-Tank-Plants-/140921866900?pt=UK_Pet_Supplies_Fish&var=&hash=item20cf990a94
Remember you dont have to make your own micros and macros like i do, you can buy them pre made, this is just how i do it as its the cheapest most cost effective way of dosing that iv found.
Their are plenty of pre made good brands out there.
Hope iv been some help