Hi Byron, I read your article a nice article.
now i have a 60 litre tank with 15 W t8 for 10 hours per day. As plants i have some crypts, marsilea hirsuta (never grows after 6 months it seems to die), Sagittaria Subulata, moss and Anubias (very ugly :( ) I use seachem flourish per week and do 10 litres wc per week.
Crypts seems to melt a lot. I have a pair of kribs and 6 pygmy corydoras. As for water parameter 16GH, 8PH, 3KH. Tap water from where i make WC is the same.
What could be the problem? Water temp is around 27-28degrees Celsius.
substrate is enriched. Seachem Flourite Black Sand. No fertiliser tab ( Do not think that i need ). Temp is 27 degrees celclius.
Light i am using T8 Day-Lite from Juwel.JUWEL Aquarium Homepage It is on for 10 hour per day. I do not know the kelvin ratings thogh.
Last thing first, on their website you can click on "Lighting" and then "Day" and it says the tube is 9000K. That's pretty high in the blue with little red. Could be one problem with crypts melting.
Another crypts problem may be your high pH. This depends upon the species; some crypts do not do well in hard, basic water, some will if it is slightly (low 7's pH). Check the species in our profiles, this is mentioned.
Crypts melting means something has changed in either water parameters, nutrients or light. Or they have been disturbed (roots). All crypts do not like changes in any of these areas, and will often melt in response to any one of them. A few species are more resilient, this also is noted in the profiles.
Your temperature is quite high--is there a reason? Corydoras pygmaeus would be happier at a lower temp (profile notes 22-26C as preferred range). A degree or two may seem trivial to us, but to the fish in the water which controls their internal temp it is significant. And 1 Celsius degree equals about 2 F degrees in this range. As redchigh noted, this may also be the issue with the marsilea.
Fish and plants "work harder" at higher temperatures, and oxygen is in less supply (more important for fish), so maintaining fish and plants within the lower end of their preferred ranges is usually better.