fertilizer advice

[fish 'n' fries]

I've a 40 gallon high tank with solidly moderate light (using ozz's lumen's/sq in calculations which make the most sense to me... ). It's probably moderately planted (based on folks opinion of heavily in previous posts...). I don't use CO2...don't plan to...and don't use Excel because I'd rather my vals don't melt. The substrate is gravel with root tabs under swords and crypts.

I had initially been doing a modified EI with ferts (no NO3...I have a pleco who seems to provide plenty)...then was reading Tom Barr's comments on that only being applicable if you have CO2...so I've decreased the EI dosing 1-2 times per week. I also had a period a few weeks ago where I ran out of K for about a week.

After these changes, I now have a hair algae problem (seems to be a theme...wonder if it's seasonal? )

I'm also now seeing brown spots in the middle and at the ends of the old leaves on my swords. My guess is it's from lack of K...maybe from a few weeks ago? Any other thoughts? I have restarted dosing K and hope it will fix...the new growth looks happy so far.

 

[dskidmore]

It may be co-incidence, but my hair algae population goes down with hyper areation. I turn off the bubble wall in winter due to heat conservation concerns, and turn it on in the summer for cooling.

 

[travis simonson]

I highly recommend going with an EI dosing regimen and testing daily (until you figure out the problem) for NO3. I suspect an N (and possibly K) deficiency issue. KNO3 when dosed sufficiently should alleviate any K issues as well as providing the necessary N that your plants so crave

 

[fish 'n' fries]

I'm quite sure it's not NO3...despite my preference for not testing...I broke down and got kits. The NO3 stays, if anything, on the higher side (20-40 ppm) thanks to the pleco. I'm hoping that since I've restarted dosing K it will resolve. How long do you need to wait after making such a change to know if it's worked?