It's usually not recommended to spray solutions containing fertilizers directly onto the leaves of plants, as it tends to "burn" them. You should pour the fertilizer solution into the soil, and only mist the leaves with de-chlorinated water to hydrate them.
If you are using good quality nutrient-rich soil substrates (like ADA Amazonia aquasoil), then there is usually no need to dose additional fertilizers during the initial grow out period, as the soil will already supply ample nutrients.
Excel is a liquid carbon supplement which helps submersed plant growth, but when grown in emersed environments, the plants already get all the Co2 they need direct from the air, so adding excel is not necessary, instead it may do more harm due to the sterilizing/caustic effect of the glutaraldehyde chemical component (which is the main ingredient in excel).
Anyways, there is usually some transition period when plants are newly added, even from emersed to emersed environments, they still need to take some time to adapt to the new conditions and develop roots. During this period, it's common to see the damaged/weaker/older leaves melting before seeing newer healthier leaves growing out to replace them.
Perhaps you can have a look at my HC DSM journal thread for some reference in growing HC emersed:
http://www.aquaticquotient.com/forum...Method-Journal!
Hope that helps!
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