Ecosystem tank with Hair Algae Problems
So. My journey into aquariums started with a vase.
2 years ago I set up a plant with it's roots in a vase of water, and I added scuds and daphnia to clean the greenwater and the root decay. Worked fairly well. Kept a terrestrial plant (a rose!) happy in water for > 6 months.
Via a predictible slippery-slope of learning more and adding more, I now have a 70 litre walsted-ish planted tank (as in... a year ago it was a gravel and aquasoil tank; but I added potting soil and sand layers above that once I learnt about Walsted. There's also a water cavity under the gravel because I used to run an undergravel filter; but I switched this off to facilitate carpet growth).
Inhabitants are assorted snails, assorted cherry shrimp, 4 amanos and a bamboo shrimp. I added the bamboo because my daphnia couldn't survive the non-stagnant circulation rate in this tank.
My goal from the start is to have the primary inputs be water and light; potentially also ferts; but the goal is to not have to feed them.
And that has... sort of worked? Until the hair Algae bloom happened.
The cherries and snails were SUPER happy for about 6 months running high light, with phosphate rich tap water. All the algae they could eat! But then the scuds died out (maybe eaten by the cherries? or just not enough detritus to feed them), and a hair algae bloom ensued.
Since then I've added the amanos to eat the hair algae, and have gone through 6 months of low light and stripping the phosphate from the water. There were some casualties (soft algae died first, my Spixi and my 3 Nerites followed soon after) which forced me to start feeding the tank again. But, the goal all along was to have a tank that didn't require food and the inhabitants were just supposed to be there for plant maintenance, so this is basically a failure of the original missio.
It's stable now on 6 hours of light a day and my inhabitants are happy. But I want to switch back to a no food tank. And for that, I need something that eats hair algae preferentially over soft algae; so the hair algae doesn't dominate the soft and clog up the tank again.
Thoughts? I think the scuds could do it. The hair algae bloom started after they died off. But I've tried re-introducing several times and they just won't take (predation by the shrimp perhaps?). Should I just add more Amanos? Or should I try fish? I experimented with least killifish briefly - super peaceful and left my shrimp alone. But starved to death whilst surrounded by hair algae; so seem not to be the solution I need (they did pick at plants and algae... but they were either eating the soft algae, or they also need meat to survive and aren't large enough to hunt my baby cherry shrimp). All the advice I can find online is on how to prevent algae... but I want algae. I just need all types of algae consumed equally so the tank doesn't get overrun by the one variety that's not getting eaten.
p.s. filter set up includes the plants, lots of high surface area rock in the tank, a bubble wall and a sponged-powerhead. I personally think I wouldn't need the powerhead if the tank was stable (testing shows zero ammonia/nitrates/nitrites thanks to the plants and algae), but as described above I'm questing for a low-intervention ecosystem here, and whenever I screw up that involves some die-off and subsequent ammonia release that the filter needs to buffer (also, the bubble wall doesn't get the flow into all corners of the tank on its own). pH wants to hover at 6, I push it up to 6.5 with additives. There is crushed cuttlefish bone in the tank to support snail/shrimp shells/exoskeletons.
TLDR; I have a tank of plants with critters that eat detritus and soft algae. How do I control hair algae without starving out the soft algae my critters need?