Interesting way to at least keep the algae at bay while you're trying to figure out what's causing it.
Now that I know what plants you're growing, I'm questioning if the light is too bright. Each of the plants you listed, except hornwort, are very slow growers. They are known for getting algae as a result. I personally found it much harder to grow those plants than I have found growing stems.
This is my basic theory regarding the balance of ferts, CO2, lighting and plant mass.
There are three things that can affect a plant's growth: Ferts, CO2 and lighting. If any of these three things are out of balance from the others, then algae will be a problem.
The basic idea is to give each plant all the ferts and CO2 they need. Give both in excess (I prefer using the EI method with dry ferts). By ensuring the plants are getting all the ferts and CO2 they need, neither of these elements will hinder the plant's ability to grow.
Next is the issue of lighting. The lighting needs to match the plants you are growing. In your case, you need low to low/med lighting since all of the plants you are growing do not require bright light. If the lighting is too brights, then algae will grow.
That brings me to plant mass. I have heard some people suggest that if they are getting algae, that must mean there are too many nutrients in the water (too much ferts). So they decide to dose less, thinking that would improve things. However, it doesn't. All it does is hinder the plant's growth.
Here's my logic behind this. The numbers I'm using are simply used to convey the concept and should not be taken in any literal sense.
When a tank with low plant mass is dosed with ferts, the water column has a high concentration of ferts, but the plant only comes into contact with so much water. So with a low plant mass, there's a lot of extra ferts left in the water column:
So it would seem logical to reduce the amount of ferts being dosed. The concept is that the low plant mass will take in all of the ferts, leaving no extra ferts in the water:
However, I believe the plants are not able to come in full contact with all of the water so rather than getting all 10 ferts, it simply receives the reduced concentration of ferts in the water it does come in contact. The plant no longer receives all the ferts it needs while extra ferts are still left in the water:
The solution is not not lower the amount of ferts dosed, but to raise the plant mass. Now there are enough plants coming into contact with the water to take in all of the ferts being dosed. All of the plants get all of the ferts they need while not leaving extra ferts for algae:
Again, let me stress that this is simply my theory! I have no proof whatsoever that this is what really happens. I came to believe this theory based on the constant recommendation from others more experienced and knowledgeable to not reduce ferts (use the EI method), but to use "nutrient sponge" plants, such as hornwort. My theory explains why this is recommended. I've also found that when I have more plant mass in my tank, the water condition is much better and I have fewer algae problems. So I offer this theory for consideration.
I'm not sure if the reason you are growing those specific plants is because those are the plants you like best or because you're concerned that your tank won't grow stems very well. Or maybe you think those plants are easier. In truth, those plants can be difficult to grow, especially when that's all the plants in the tank. I have found stems to be much easier to grow!
Another plant you might like to try are Crypts. They are tough as nails and require very little maintenance (I have only had 1 Crypt melt on me, but it grew back quickly).
I can't say at this time that your over cleaning is removing necessary ferts from the substrate since you are not growing plants that are rooted into the substrate. The concern then shifts to removing/disturbing too much of the beneficial bacteria, causing the tank to go into mini-cycles. I know I did this to my tanks because I cleaned way too much.
I think the compulsion to over clean needs to be reviewed in your own mind. What is the real concern if you don't vacuum every speck of debris in the substrate? What will happen if you leave it? Will it cloud the water? Pollute the tank? Make the tank look unkept? And what are you receiving by over cleaning? Do you feel you are taking excellent care of the tank? Do you think it is necessary to clean tanks to that degree?
I think if you find the real reason as to why you feel the need to over clean, then you can take a hard look at whether the concern is truly valid. If you can change your thinking around, then you can see that over cleaning is not beneficial and can be harmful, while not over cleaning is actually better for the plants, inverts and fish.
I will say that my tanks are their cleanest when I have a high plant mass and just simply do water changes without messing with the substrate. The plants clean the tank for me. I now see the mulm as a good thing, like an enriched soil. Too sterile a substrate is not good. So when I see the mulm build up (I can see it where the substrate is up against the glass), I feel very good about it. I feel that I have a truly thriving tank, not a sterile one. It does not harm the water quality, the water is crystal clear, the fish/plants/inverts do fine with it and I'm not constantly disturbing the beneficial bacteria. Try to change the way you look at the mulm which will go a long way towards no longer feeling the need to over clean.
Whew! Did anyone really read all that? :blabla: [smilie=l: