Vallisineria problem

[Terry]

Probably spelt the plant name wrong, but anyone know what causes the ends of the leaves to turn brown and decay?  I have always had some brown tips but now I am getting large numbers of brown leaves.  Plants still seem to spread.  Other plants are OK but not growing with any vigour.   Any ideas welcome.  Tank is 30 gal with HO T5 6700 and 10K. Nitrates 10-20ppm.  12 cardinals.  Excel fertilizer used.

[magnosis]

Sounds like a Potassium deficiency, especially if only the older leaves are affected.

http://web.archive.org/web/20080709055105/http://www.csd.net/~cgadd/aqua/art_plant_nutrient.htm

http://www.finostrom.com.gr/images/aqua/fertilizers/map.htm

[sas]

I've had problems with my vallisneria when using excel, could be just my tanks though?
Hopefully the plant experts will chime in here, since I can destroy aquatic plants
in a heart beat.

[Jeff1192]

In my experience Excel in recommended doses won't cause any problems with Vals. I would suggest trying fert tabs in the substrate. If it's only the older leaves it sounds like a defficiency to me. I always used to put tabs under my Vals when I had them and they did much better with them.

Jeff

[Terry]

Thanks for the advice, all.  I think however I figured out my problem.  The plants (vals only) started to rot on a major scale so I tore the tank down and was startled to see how dirty the gravel was.  Now I change water weekly and do so using a gravel cleaner so there was not much "dirt" but when I started to swish the gravel around in a bucket, the water came out black.  Every grain was heavily coated with something (scum?).  So, lesson learned, 12 years is a bit much between tear downs. But  until  a few months ago, all was well.   I do use a phospate remover and when required a nitrate remover - so very little algae and in fact my tank is probably nutrient poor.  Things are now stable, waiting for crpt melt due to the water change.

Terry