[Ritobasu]

I have a 40 breeder medium/low light tank with mostly crypts and some floaters (Water Sprite, Water Lettuce, and some Duckweed I'm trying to get rid of). Since I plan on resuming dry fert dosing along with replenishing my Flourish root tabs with Osmocote ones, I'd like to try Excel dosing again. I've been doing only water topoffs and dosing as lean as possible before my duckweed infestation, and my crypts have barely grown in the 3-4 months they've been established. The weekly dosage was 1/4 tsp of KNO3, 1/16 tsp of KH2PO4, and 4ml of Flourish Comprehensive for micros.

My questions are:

Can Excel be dosed at any time during the day, even with its 11-12h half-life span?

Will my tank suffer any algae issues if I skip Excel dosing for anywhere between a few days to up to a week or two? I've read articles from Tom Barr about how algae takes advantage of fluctuating CO2 situations better than plants, and with the absence of Excel (which can work as an algaecide) for a couple of days to a couple of weeks, I'm worried about having outbreaks that my Amanos and Nerites can't help mitigate along with taking away extra nutrients from my plants...

Is it better to up my fert dosage, or continue to dose lean like before? I still want to minimize water changes to at least once a month, or even longer.

 

[Hoppy]

The best argument I know of for dosing so the plants have enough of all of the nutrients that they can grow as fast as the light intensity allows them to, is that doing so gives you a chance to see what that type of plant growth looks like. Then, you can start reducing how much you dose, for any of the nutrients, and you can watch for adverse effects on the plants. Using that you can figure out what the lowest dosages are that give you good growth.

If you start out with low dosages it can be much harder to identify the dosage that let you get that same good growth. You may have an algae infested tank of half dead plants to start from - exaggerating, perhaps, but it is a significant difference.

Another possible problem is that as the plants are growing, and building up plant mass, usually accompanied by having more plants - runners, cuttings replanted, etc. - you will need more nutrients to feed them, so there is no dosage schedule that will be optimum for your tank for very long. Do you want to continually be adjusting the dosages? If so, it can be done, but if you don't, it is probably not the best idea to start with very low dosages.

Excel doesn't act exactly like CO2, as far as encouraging BBA by allowing the concentration to fluctuate is concerned. But, I think I saw that missing dosing Excel for a day or two does encourage algae to some extent. It just makes good sense to dose it every day, and try to dose during the photoperiod, ideally at the beginning of the photoperiod.