Hair algae coinciding with potassium deficiency?

If any nutrient is missing the plants can't grow. Then the algae can grow more/better.
Poor circulation promotes hair algae as well. Long hrs of light do also.
Had it in my tank @ 10 hrs and dropped to 7.5 and gone. Took a while though.
Depending on the level of plants the 20-40 doses may not be too high.
Don't know if Swords are one of them but certain plants use more Potassium.
I do know that Wisteria is one that does. You may have enough of the other nutrients so you might want to just add more KNO3 or K2SO4 instead of going to the 20-40 doses. For example if you are using just a bit less than 1/2 tsp per dose you can try adding an additional 1/8 tsp each time with it. I know the EI gives weights instead of tsp but you can convert it on/under "and I am calculating for" ..."the results of my doses". This can use tsp. It says 1/4 tsp for the 10g tank which is why I picked 1/2 tsp for yours. If this is not clear, PM me.

Holes in the upper leaves are not potassium deficiency. Holes in the lower leaves are potassium deficiency if they are surrounded by a chlorotic boarder.

Post photos of your plants to be sure it is potassium deficiency.

Thank you for the info Raymond. My tank just over 90% planted and I think circulation was an issue...I did a major trim and things are swaying in the breeze once again. I'll increase the K2SO4 dose because I'm good on nitrates usually. When I was using the 20-40 regimen I actually used the 10-20 for KNO3 because my nitrates are always high.

Zappins, I hacked back all of the stem plants and threw a lot of the tops away...the pin holes were on the upper half but were not new growth. It was on leaves that developed over a week ago. If it shows again I'll be sure to get some photos for you.

I had the same thing some of my compacta had pinholes on upper leaves and I started to see hair algae on the tips of the compacta. I thought it was a potassium deficiency as well, so I doubled my KS04 dose. I wish there was a way to measure potassium levels. That tank has wisteria so I figured it was hogging potassium. BTW H202 does some serious damage to hair algae.