Agreed. Thankfully, our meltdowns are not as epic or as costly as the reef side can be.
The variable, of course, are 1) plant uptake levels and 2) other things in the water column that are not known to us at the moment. The controlled water change where you start with zero water and add to it, results in you having a very good idea of the input water. What you don't have a very good idea about is what's in the water you are removing. Yes, we can guess at nutrients that are being removed as a percentage of your water change. We can also guess at other things such as DOC, etc.
Here's an example of what I'm talking about. Let's just say you use RODI water and you had a fixed formula of nutrients every week. You do a 50% water change weekly.
Based on the above, the accumulation calculator can give you some insights. However, it doesn't factor in plant uptake of nutrients. Since you are not measuring prior to a water change, you can't tell me how much magnesium your tank consumed. Over time, the nutrients in your aquarium will not be what your calculations are.
If what I just wrote above makes sense to you, how do you solve for it without testing?
I realize that this may be theoretical but it may explain some of the mystery long-term issues some experience. This is not to mention the variable of your substrate. It absorbs nutrients (and other things) over time. What does that do longer term?
If you're like me and don't like situations where you are doing something simply because it works without understanding what it's doing, then this is the stuff you lay at night thinking about. I know, I know, I'm weird.
No I totally get it. It's good to see that I'm not the only one that goes down rabbit holes lol.
From the accumulation perspective, I think doing a much larger than normal water change every so often will help address accumulation. Even then you'll still get some accumulation but knowing what your plants are consuming would be huge. The challenge is understanding that with fish producing waste and plant matter decaying in the tank, and to what extent does waste trapped in your substrate affect things. I planted a few plants last night and as soon as my tweezers began pushing the plants into the sand, huge orange/reddish dust clouds of waste rose up into the water column. What that told me is that I need to do that manually during water changes going forward.
What's a little frustrating is how readily available all manner of tests are on the reef side, but on the fresh side the options are far more limited, and even to some extent the quality of the test kits can be dubious if you do find an oddball manufacturer of an uncommon test kit. This is one area that I believe needs vast improvement. For example, look at Hanna. The vast majority of their checkers are marine checkers. From a business standpoint, they're putting their money where the most ROI is, which is the reef side. Reef is definitely a very small part of the market in comparison to freshwater. In all honesty though, that's where the wallets are much larger as well, but I'd wager a guess that planted is likely about the same market size as reef is. Even at that, how many people are going to want to test stuff other than NO3 and PO4? To test K, it seems like there's only one option, and to test for Fe, you basically have two. So it makes sense that if it's not as easy as the same reagents being manufactured as for marine, then they'd focus on the reef side since they know there will be a return on investment whereas I don't think they'd see an ROI on the planted side.
When I started back up earlier this year, there were two schools of thought on the planted side - lean or EI. Both required 50% weekly water changes, but the former required a much better understanding of plant health to visually adjust your dosing, while the latter was like using a machine-gun to hunt doves. I went with EI because almost everyone with expertise and experience said you didn't need to test and it was idiot proof. After a decade in countless tests on my reef tanks, hearing that testing was pointless was a godsend lol.
Honestly I think the only way to really solve the problem is through sending water samples to a lab for a full analysis of what's in the water. I've never done this myself, but I know several reef keepers who went this far and from what I remember it wasn't inexpensive.
Honestly I think a great start would be sending a water sample off to a lab to get a full understanding of what is in the water. From there it would be easier to know what you're dealing with and make decisions on where to go next. I think the only thing that would send me down this particular rabbit hole is running into an issue that I can't solve and can't explain. That's where I was a few weeks ago. But the problem resolved itself for the most part so my assumption is that something I'm doing is working. While it does bother me that I don't know exactly what it is I'm doing that is helping, I'm not sure the costs of lab testing would be worth it unless it was $20 or some other nominal fee.