EI and the importance of the "rest day"

I believe a Rest Day is to allow your plants to use extra nutrients in the water column. You are not "wasting" as many nutrients as you are when dosing straight through. It also keeps everything nice and orderly which will help you to pinpoint any problems that may arise along the way. Humans like order. We also like holidays. A Rest Day will give your arms, measuring spoons, fish, and plants a holiday. Perhaps there is some logic to that feeble explanation? I suggest that you do what you want to do with your dosing as long as it is working for you. If it is not broken, don't fix it.

If you use calculators most of them is based on a rest day. Without the restday your "end" levels of nutrients would be a bit higher. Like if a calculator targets for example 0.2ppm FE you might end up with 0.3ppm FE if you skip the rest day and do your weekly 50% WC. Thats why daily ei dosing is cut a little more than 50% of the standard ei levels. Not sure if there is an actual reason though for the rest day more then keeping an even dosing number for reasons of simplicity, 3 x macro / 3 x micros.

I think I'm going to utilizing the rest day this week and see what happens. Today is water change day and the new schedule will call for me dosing today as it would be the start of the week.

The rest day is just the day you don't happen to do any dosing since, if you're following "classic EI", you're doing micros three days per week and macros three days per week. It's the day in the week that's left. It's as simple as that.

I don't believe there is any benefit to a "rest" day. Instead, I prefer to just alternate macro and micro dosing. When I do water changes I dose after the water change, with whichever is scheduled for that day - the one I didn't dose the day before. If you want to save fertilizers, just do some testing to optimize the dosage sizes. (Reduce one nutrient dose slightly, and watch to see if the plant growth is adversely impacted. If not, reduce it slightly again and watch for adverse effects. Keep this up until you can see an adverse effect, then go back to the previous dosage, and start the process on another nutrient, until all have been reduced appropriately.) As your plant mass increases you will probably need to nudge your dosages up a bit to supply the higher demand.

Well with the schedule I've been using I feel like I've been stripping the water column of ferts. I've never dosed anything after my water changes on Sunday and feel like mentioned above the rest day would allow nutrients to be used up before the water change the following day.

Why worry about whether or not the surplus nutrients are used up before a water change? Those chemicals are very cheap unless you have a very big tank. So, why not follow a schedule that works best for the plants, whether it wastes fertilizers or not? Remember, the 50% water change is done specifically to remove surplus nutrients, and, as a bonus, it also removes other water contaminants, and is appreciated by the fish.

Hoppy said:

Why worry about whether or not the surplus nutrients are used up before a water change? Those chemicals are very cheap unless you have a very big tank. So, why not follow a schedule that works best for the plants, whether it wastes fertilizers or not? Remember, the 50% water change is done specifically to remove surplus nutrients, and, as a bonus, it also removes other water contaminants, and is appreciated by the fish.

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I'm in no way trying to conserve my ferts. I was more worried that I was shipping the water column on my WC day and adding nothing after my water change.

Nlewis said:

I'm in no way trying to conserve my ferts. I was more worried that I was shipping the water column on my WC day and adding nothing after my water change.

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That's why I dose right after I do a big water change. I want adequate amounts of nutrients available at all times. I often dose the macros then, even if it is the micros turn, because I believe we are far more likely to run out of nitrates than any of the micros.

Hoppy said:

That's why I dose right after I do a big water change. I want adequate amounts of nutrients available at all times. I often dose the macros then, even if it is the micros turn, because I believe we are far more likely to run out of nitrates than any of the micros.

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Well it started this week. Today was the final micro day and tomorrow there will be no dosing. Sunday I'll do my WC and dose macros and I'm considering whether or not to dose some gh booster. I still don't know whether I need the booster or not but I guess it can't hurt.

Hoppy said:

That's why I dose right after I do a big water change. I want adequate amounts of nutrients available at all times. I often dose the macros then, even if it is the micros turn, because I believe we are far more likely to run out of nitrates than any of the micros.

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With the right dosing one should not run out after the WC but close to it, that would be the most efficient dosing in my opinion anyways. I just found out my issues are not with Nitrates but this is most likely due to 40 tetras and other small fish plus around 100 amano shrimp. But it seems my phosphates are running out. So for me KNO3 can safely be halved and the KH2PO4 needs to be increased by 50%. Not sure the thought of EI as set it and forget it are that correct. One could apparently overdose one thing and underdose another depending on the tank it is used on.