Hi and Happy Holidays to you!
Again, thanks for posting this as it will help you to diagnose the problem and learn from it. It will also help countless others who experience the same problems.
So I think your issues are stability related. You don't mention how old the tank is but it seems to be behaving like a relatively immature tank. You've also made a lot of changes so that adds to the instability. Once the tank settles in and you stop making meaningful changes, you will win this battle. No question about it so stay positive and stay the course.
I hate to give you homework but I would highly recommend that you download and complete the worksheet we have that captures a lot of data about your tank. This will help you to keep track of what you're doing and will allow us to quickly get a summary of your tank and its parameters. You can download it from our Resources section:
Aquarium Fertilizer Template. If you complete it and post it here, it will help us to continue to diagnose.
Fundamentals at work in your tank
In my experience, instability and resultant poor aquarium plant health are the two things that mainly lead to algae issues in the aquarium. You need to address each one and they both take time.
Instability comes naturally from an immature tank. It can also be from a change that impacts plant health/growth. Either will give algae the opportunity it needs to quickly grow as its simple system can get what it needs much easier than the more complex aquarium plants. However, this simple system is also its Achilles heel.
Part of this simple system is its ability to take up dissolved organic compounds (DOC) much better than plants. I've also read that algae colonize aquarium plant leaves because the plant is releasing DOC from that leaf that is intentionally decaying. This would explain the GSA and Staghorn you are seeing on your plants' leaves. The infected leaves are not doing well.
First step - stability
I would recommend that you methodically confirm that each system is working well with your aquarium and that it is as it should be. For example,
- Make sure you are providing enough light for the types of plants that you have. This can be enough PAR and enough photo period.
- Make sure the CO2 is optimized. Confirm your pH is properly calibrated.
- Change from DIY fertilizers to a good, complete commercial product and dose appropriately to your light and CO2.
- Do 50% water changes weekly and vacuum the substrate properly.
- Trim dying or dead leaves, turkey baste any hardscape, clean your mechanical and chemical filters.
- Surface skim.
- Make sure your temperature and water level don't swing too wildly.
- Stop chasing individual nutrient numbers. Use quality (and unexpired) test kits for the important elements (NO3, PO4, Fe).
- Make sure your makeup water is controlled and stable.
Honestly, I think your well water represents a variable that you can't control. It may or may not be causing an issue. We have no way of knowing. However, the only way to gain control over this is to use RODI and I've read it's a pain for you. It was for me too. I feel ya.
If I were you, I would make sure everything else becomes stable and at the right level. Give your tank time to stabilize and see how it's going with the well water. If the tank is still giving you issues, it may be something in the water otherwise your plants would have adapted to it. My thoughts would be to run the well water through a carbon filter first to see if that fixes the issue. If not, then and only then, would I be thinking RODI.
Second step - bring the hammer
As you've heard a million times, you have to fix the root cause of the problem and not just mask symptoms. By doing step 1 above, you are dealing with the root cause of the problem. Once that is done, then you can address the algae with the right hammer.
My philosophy is to bring the right tool for the job. You don't need a sledge hammer when a nail hammer will do just fine. Of course, don't bring a screw driver when you need a hammer! (Come on, we've all been there!).
For persistent staghorn, you either trim the leaf if you see that it isn't healthy and the plant is on its way to drop it or you spot treat it. I'm not a fan of whole tank treatments for staghorn as that is bringing the sledge hammer. Usually, staghorn will affect areas or just specific plants.
If you decide to treat the leaf, then get yourself some Seachem Flourish Excel and a plastic syringe from the drug store. During a water change when your flow is off, spot treat the leaf with the Excel. This works well for GSA also. Actually, any glutaraldehyde product will work (Turbo Plus, Phyton Git, etc). Even H2O2 will work but I prefer the Excel as it works better during the day. H2O2 should be dosed at night.
Over the next few days, you should start to see the staghorn turn white or pink. It will then disintegrate over time or can be more easily removed by hand. Sometimes, I've had to dose the Excel a few days straight to get the effect.
Looking forward to seeing how your tank starts to stabilize and turn around.
