going by your height and lighting assumptions i should never have anything but algae surviving in my tank (the one in question). assuming that co2 is necessary at that point my plants should all be dead too... from algae overgrowth. my tank is 36" x 18" by MAX 10" deep with 52 watts cfl and t8 over it. all 6500k and 5500k. i use an air pump to raise my co2 levels. there are many ways to skin a cat... some easier than others.
yet still my tank (by your calculations too low in co2 and photoperiod way too long) HAS NO ALGAE ANYWHERE!
i fixed all my issues with a floater, air pump for co2 addition, and dosing kh2po4 and kno3. all is absolutely well and dandy.
btw floaters don't need co2 since they can get it from the air above and therefore can help balance a tank pretty well by blocking light to plants that may be getting too much.
kreesdqban... look into florin axis and/or flourish excel for carbon if you plan on adding it. fluctuating co2 and or dialing it in just right little by little can be more headache than it's worth. if you do everything right and your co2 fluctuates you'll have just as many issues if not more than you do now. it's best to start with plants the easiest possible route. adding too many variables at first puts you behind in the game more often than not. a lot of people give up for these same exact reasons. then all the hard work and money invested is just a waste and you are left with nothing to show for it. living by the rules KISS (keep it simple stupid) can really help you with your success and help you take it step by step. at this point providing shade to your slower growers and getting down your npk dosing is not only the cheapest but also the simplest first steps. if you feel the need and are confident in going further then take the next step.
anyway... i don't think my tanks are the ones with problems right now. how bout we focus on the op's issues?
yet still my tank (by your calculations too low in co2 and photoperiod way too long) HAS NO ALGAE ANYWHERE!
i fixed all my issues with a floater, air pump for co2 addition, and dosing kh2po4 and kno3. all is absolutely well and dandy.
btw floaters don't need co2 since they can get it from the air above and therefore can help balance a tank pretty well by blocking light to plants that may be getting too much.
kreesdqban... look into florin axis and/or flourish excel for carbon if you plan on adding it. fluctuating co2 and or dialing it in just right little by little can be more headache than it's worth. if you do everything right and your co2 fluctuates you'll have just as many issues if not more than you do now. it's best to start with plants the easiest possible route. adding too many variables at first puts you behind in the game more often than not. a lot of people give up for these same exact reasons. then all the hard work and money invested is just a waste and you are left with nothing to show for it. living by the rules KISS (keep it simple stupid) can really help you with your success and help you take it step by step. at this point providing shade to your slower growers and getting down your npk dosing is not only the cheapest but also the simplest first steps. if you feel the need and are confident in going further then take the next step.
anyway... i don't think my tanks are the ones with problems right now. how bout we focus on the op's issues?