Over in the IFC fertiliser thread (and excellent tool btw.) I asked a question about front loading and accumulation, which I thought was worthy of further discussion/exploration.
My question was why, with front loading, one only doses for the replacement water and not the whole tank. The answer to that was to avoid accumulation. Now, if I understand correctly, with daily EI dosing, we do regular 50% water changes to keep accumulation in check. My question though would be, why would we be more concerned with accumulation when front loading than when daily dosing? The accumulation that occurs would conceivably be the same amount irrespective of approach. So, the question still remains - we could dose for the whole tank and front load, do a 50% water change to keep it in check, or if we are genuinely concerned with accumulation, then perhaps we should only does for the weekly water change amount even if dosing on a daily basis.
I'd be interested in others' views and also if I've got completely the wrong end of the stick.
Front end loading and dosing for replacement water and not the whole tank are two entirely different topics.
Contrary to what most believe people like me who front end load do it to keep nutrient levels more stable. Dosing every other day typical leads to a very low nutrient level right after a water change, and then the levels rise and peak right before the next water change.
I can use my tank as an example. My plant uptake of nutrients is just a little higher than the tank generated nutrients (fish/feeding/waste). Let's say I were to dose 12 ppm NO3 weekly and perform a 2/3 water change. If I were to dose the traditional way I would perform a water change then dose macros every other day. This is what my nutrient levels in the tank would look like. Pay attention to the daily NO3 level in week 11. Notice how the nutrient levels would start very low then rise until the end of the week. Many sensitive species hate that dip in nutrients.
Now let's take the same dosing but dose all weekly macros right after a water change. Notice the difference in the daily NO3 level in week 11.
I think you would be surprised at how many people are now using this method. Personally I started front end loading about 5 years ago or so. My main thought was that if there is an "optimum" amount of nutrients in the water column that plants prefer, then why not try to keep it there?
If anything else it sure is a lot more convenient. And even if someone does not front end load, most would benefit from dosing something like 50% of the weekly total right after a water change then two 25% doses during the week. You want to avoid that big drop of nutrients from the water change.
Now as to dosing based on the amount of water removed or the entire tank it is simply a matter of semantics. It's two ways to report the same thing. I started a crusade years ago to get people to think of "target" dosing, but old habits die hard.
The reason I think it works better is that a lot of times people try to copy someone else's dosing. But what they don't realize is that if they are not on the same water change schedule, then they are not providing the same level of nutrients in the water column. It all has to do with accumulation.
If you change less water, then your accumulation will be higher. If you change more water then your accumulation will be lower. By a lot.
There is simple formula to calculate the theoretical maximum accumulation of fertilizers. It's the weekly ppm divided by the water change percentage.
So let's take NO3. If someone is dosing 12 ppm weekly, this is how water change percentage affects accumulation.
12 ppm weekly at 25% water change is 12 ppm/0.25 = is 40 ppm max NO3 accumulation.
12 ppm weekly at 50% water change is 12 ppm/0.50 = is 24 ppm max NO3 accumulation.
12 ppm weekly at 75% water change is 12 ppm/0.75 = is 16 ppm max NO3 accumulation.
So you see 12 ppm NO3 dosing can mean a lot of things depending on the water change schedule.
If our "target" in the water column is 24 ppm, then we would report it as a 24 ppm target dose. It is exactly the same as dosing 12 ppm NO3 with 50% water change. So again it's two ways of saying exactly the same thing.
I hope that makes some sense but I am guessing you are sorry that you asked. Now I need to lie down with a cold compress on my forehead for a few minutes!
😀
