I have a planted 29 gallon aquarium with only 1.25wpg and everything but my micro sword seems to be doing well. I have a topsoil and aquasoil substrate below a 1" sand bed. I tried using some Leaf Zone fertilizer and it showed no effect . . . and then my water then turned green! The green water became a major setback and I'm presuming the Leaf Zone was the cause. I'm planning on adding some blyxa japonica and an orchid lily which (of what I researched) are relatively high light and because my light is not exactly "up to par", I was deciding on *possibly* adding some co2. Will this help out my micro sword and the soon-to-be plants and is there any negatives like green water with low light in terms of the co2.
Any comments and past experience advice would be great
c02 as long as it is consistent would not hurt, but you really need to bump your light up to 2.0 watts/per gallon. Too much light will ignite an algae bloom, but with too little light your plants will suffer, and if your fertilizer ends up being excessive, keeping in mind that in a low light tank nutrient uptake by plants tends to be much lower, you will end up with problems. Also keep in mind that if you unwittingly go overboard on the ferts in a low light tank and are not doing frequent water changes, excesses can easily build up and potentially harm your fish/shrimp. It is all about being patient and finding and maintaining a balance. IME, that is a lot easier to do with a low light tank than a high light tank, unless you use ADA Aquasoil with a high tech setup. IME, lol, it is sometimes a lot easier to find the balance then to keep the balance over the long term. Once you lose the balance, things tend to quickly spin out of control and go from bad to worse unless you can find the source of the imbalance and nip it in the bud. Sometimes with high tech tanks that is like trying to find a needle in a haystack.
My suggestion based on my experience, is raise the light levels to 2.0 watts per gallon, inject with DIY c02 from one 2 litre bottle(optional) and use Seachem Excel for supplemental carbon(assuming you don't have any other plants: vals, egera densa, riccia, etc.,) that are sensitive to the effects of excel.
The green water should resolve itself over time. I have never had green water, but from what I have read about other posters' experiences who have had green water breakouts is that they usually tend to resolve themselves once the tank matures and acquires a proper balance. One quick way to take care of a green water problem is to invest in a UV sterilizer. A diatom filter may work as well. I often wondered that the reason that I have never got green water is because I use Seachem Purigan in all my filters. This is just speculation and I cannot be sure. But others have suggested not getting green water breakouts by using Seachem Purigan in their filters.