The algae is much more likely due to the light being too much, which can be intensity or duration or both. I would deal with the duration first, and reduce it. You recently raised it when you saw the algae, but I would suspect it should have been reduced. Seven hours may be sufficient. Remember this is not isolated, the light has to be balanced with available nutrients, and this balance has to be sufficient for the plant species. You do not have fish yet, so that also makes a big difference. Ammonia will be more when fish are present, both from their respiration and the decomposition of their waste in the substrate, and plants will readily grab all of this fast. There is also the plant substrate again, this is probably doing something.