BBA and dying hornwort/frogbit
My 5-year-old low-tech planted tank has been great for several years, but two problems have come up in the last 9 months or so: black beard algae, and I suddenly can't keep floating plants alive.
My conditions: ~65 gallons, Fluval 406 cannister filter, Current USA Satellite Plus Pro LED lights at about 40% brightness (with a bit of emphasis on red and less on green) run for 8 hours per day, Eco-complete substrate, very hard water at pH ~7.8, ammonia/NO3/NO2 very low or undetectable, ~80 degrees F, lots of Vals and Crypts with some Anubias in a dim corner, moderately populated with brown-tailed pencilfish, dwarf hovering zebra loaches, paskai rainbowfish, a pair of German Rams, and Amano shrimp. I do ~40% water changes 3x per month, I treat 1-4 times per week with Fourish Excel, and I feed a variety of dried and frozen food plus live grindal worms.
My tank got ich about 9 months ago and I treated with salt and increased temperature, and ever since then I can't keep floating plants alive. I was throwing away handfuls of frogbit and hornwort before the ich, but now the frogbit slowly dies and only the young tips of hornwort hang on. I tried re-buying both as well as adding Salvinia, but no luck. Around that time, I also started getting BBA. I slowed it way down by removing all wood and treating with H2O2, plus buying more Amano shrimp, but it's starting to come back.
Here are my questions:
1. I've got 5 years' worth of mulm in the substrate--when I clean the tank I just wave the siphon above the substrate so as not to disturb the plants' roots. Is this a constant phosphate source for the BBA? Is it time for me to take out all the plants and really clean out the substrate? (I'll add here that it's really easy to over-feed with grindal worms.)
2. I'm totally winging it with lighting, because LEDs don't conform to watts/gallon measurements and I've never dropped $1K on a PAR meter. Should I change my lighting? I decreased the brightness and daily duration months ago to what I described above, but I want my plants to thrive and outcompete the algae. Plus, my tank was fine for four years with brigher light for longer duration than I'm currently using. No direct sunlight from windows is hitting my tank.
3. I used to get shade from all my floating plants, but now I don't. I'm totally clueless about why these plants won't grow when the crypts and vals are all fine and when I've done a ton of water changes in the 9 months since the salt treatment. ANY advice on this one would be greatly appreciated!
4. Should I invest in a bunch of additional tests and supplements (e.g. iron, phosphate, etc.)?
Thanks for taking the time to read this long post! I'd love any advice you all have got!
Last edited by hirundo; 05-03-2020 at 05:29 AM.