Microsorum w/ black blotches

[dhopey]

https://picasaweb.google.com/dave.hopey/Microsorum#5582966593585181650
https://picasaweb.google.com/dave.hopey/Microsorum#5582972980477156098

Above iare photo links to my M. pteropus 'windelev' fern w/ black necrotic spots and an in tank shot from my 29 gallon. The problem is getting particularly bad and all Microsorum varietys are affected... all other plants show no signs of nutreint deficency/slow growth, including the moss/liverworts pulling ferts and CO2 exclusively from the water column exclusively like the ferns do.

here are my specs...
CO2 50-37ppm (pH7.0-7.2& 20dKH) in addition to CO2 mist from the canister filter output
CO2 is stable and consistent from a pressurized systems, w/ glass ceramic diffuser fed to canister inlet
plenty of water flow for a 29 gallon (1 canister filter and 1 powerhead
1x65watt CFL biax lamp or 2.2wpg
1/8tsp kno3 daily or 3.3ppm NO3 daily
1/32kh2po4 daily or 1ppm PO4 daily
.1ppm CSM+B daily
.1ppm Fe DTPA daily
5mls excel daily

Ive kept these parmeters pretty consistent for months and the problem persists I believe the ferts and CO2 have always been were they need to be. Plants grow fast and healthy in this tank, except the ferns. I thought these black spots were a CO2 issue, but my good, consist CO2 contridicts this idea. Could it be an excel sensistivity? Too much light even though my co2 should allow it? Anyone else get the necrotic spots on their ferns?

 

[Crispino Ramos]

Trim the leaves with black spots, it could be a virus or fungus infection. It used to occur on my Java fern but it didn't continue on the new leaves after I trimmed the leaves with black spots.

 

[dhopey]

Well I have tried trimming them back to bare rhizomes before, the new growth looked good, but after a few weeks the necrotic spots came back. I fully plan on getting rid of the affected leaves but would prefer to wait until the new growth is healthy and Im confident I can keep it that way.

I also noticed today in addition to the black blotches, there are also some pinholes developing as well.

 

[Crispino Ramos]

Try Hygrophila salicifolia - it's just as effective as java fern for aquascaping.

 

[GillesF]

I think this is a CO2 defficiency, how do you measure your CO2 level? With the Ph-KH table?