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Front Loading and 50% Water Changes

Are 50% water changes enough to maintain my target numbers in a heavily planted tank?
Yes. You just adjust based on the volume you are removing.

If you front load then dose the new incoming water (50% of the tank volume) to your "target".

Or you could dose say 1/2 the weekly dose after the water change, then two more doses during the week.
 
Yes. You just adjust based on the volume you are removing.

If you front load then dose the new incoming water (50% of the tank volume) to your "target".

Or you could dose say 1/2 the weekly dose after the water change, then two more doses during the week.
Thank you @GreggZ, I was thinking 50% might leave you short weeks down the road with plant uptake and such.
 
I'm following the same approach, but I'm still testing it out.

After 50% wc:
1) a single dose of tank volume (example 300L) + 2/3 weekly dose of tank volume
2) a single dose of wc Volume (so 150L) + 2/3 doses of tank volume (so 300l)
3) a single dose of full week of ferts(except for micro, that I would still give 1 dose after wc + 3 weekly dose), but for wc Volume (so 3 doses for 150L)

Which one is the "correct" approach?

Edit: well I reread, "your target" in my case is a "single dose" 3 times per week.
 
Personally I only like front loading when doing 75%+. With less wc volume you wind up with either a huge surplus at the beginning or a deficit at the end

Since you're only dosing for changed volume I think it's likely that you'll have a deficit later in the week with 50%

My macro mix adds 4.5/1.5/6 per dose (whole tank vol). I went back to 50% a few months ago. What I do now is 2 doses after the water change and then 2 more through the week in typical 3x week fashion

But the way youre dosing the reservoir you cant just throw in an extra dose mid-week or whatever. It might me a good idea to adjust for whole tank volume, or just raise youre ppm for changed vol. Either way is doing the same thing

Whole tank vs changed vol are just different ways of keeping up with the same thing - what you add to the tank. 5 ppm at changed volume is leaner than 5 ppm at whole tank. And it gets leaner and leaner the less wc volume you do
 
Personally I only like front loading when doing 75%+. With less wc volume you wind up with either a huge surplus at the beginning or a deficit at the end

Since you're only dosing for changed volume I think it's likely that you'll have a deficit later in the week with 50%

My macro mix adds 4.5/1.5/6 per dose (whole tank vol). I went back to 50% a few months ago. What I do now is 2 doses after the water change and then 2 more through the week in typical 3x week fashion

But the way youre dosing the reservoir you cant just throw in an extra dose mid-week or whatever. It might me a good idea to adjust for whole tank volume, or just raise youre ppm for changed vol. Either way is doing the same thing

Whole tank vs changed vol are just different ways of keeping up with the same thing - what you add to the tank. 5 ppm at changed volume is leaner than 5 ppm at whole tank. And it gets leaner and leaner the less wc volume you do
Thats what I was thinking. The 50% could leave me short on the back end. I tested nitrates before the water change and it was real close to my tank target of 30. But P and K could definitely be short.

I wonder if a mid week splash of P and K would work. But how much?
 
Its anybody's guess. You could just run the math and adjust the storage container ppm higher to put the same thing in the tank as 75%

Going to 50% means you'll be dosing leaner if you keep the same ppm (because youre dosing for changed vol), so just raise them up

Or just try it like it is and see what happens, may not need to do anything
 
Thats what I was thinking. The 50% could leave me short on the back end. I tested nitrates before the water change and it was real close to my tank target of 30. But P and K could definitely be short.

I wonder if a mid week splash of P and K would work. But how much?
If your NO3 is about at your target right before a water change that is perfect. So your tank is generating about the same amount of NO3 that plants are taking up. Same goes for my tank.

As to PO4 I would do the same weekly test. Once right after a front load of ferts and one right before the next water change. If it's really going down then add a mid week dose of PO4.

I don't test K but dose quite a bit so not too worried about that.
 
Personally I only like front loading when doing 75%+.
As you say, when we calculate accumulation and consumption it all depends on water change volume. Years ago I started doing 50% water change as is common practice for EI, but I've never understood why 50% would be better than say 70%. I see several benefits of more than 50% WC, and frankly no downsides, so for years I've been changing 70% weekly. Keeps organics low, removes algae spores, and gives a more predictable concentration of ferts over time.
 
As to PO4 I would do the same weekly test. Once right after a front load of ferts and one right before the next water change. If it's really going down then add a mid week dose of PO4.
I just checked it, and it wasn't even 4ppm. I changed water last night. My Spatulata stems rotted last week. Joe said they are a good indicator of low PO4. I'm guessing my 50% water changes will not keep up with this plant load.
 
What is your accumulation goal?
I dont have one. To me the variation in plant uptake at any given time, relative to what the overall plant mass is, makes it pointless to aim for a certain amount in the water because the ideal is never a static number

Although I can tell you roughly what the totals in the water are, or need to be, for my reference I just go by total dose per week and adjust from there

My tanks grow fast and get hacked down regularly, and not everything at the same time. This overgrown 75 gal monstrocity is gonna suck up a ton more nutrients than one with everything trimmed low and neat.

20240305_183804.jpg

Next week this one will be low and neat while two more become just like it. So accumulation and uptake change dramatically, impossible to monitor much less target. Totals for the week are a known constant, an accurate number easy to go up or down from
 
I dont have one. To me the variation in plant uptake at any given time, relative to what the overall plant mass is, makes it pointless to aim for a certain amount in the water because the ideal is never a static number

Although I can tell you roughly what the totals in the water are, or need to be, for my reference I just go by total dose per week and adjust from there

My tanks grow fast and get hacked down regularly, and not everything at the same time. This overgrown 75 gal monstrocity is gonna suck up a ton more nutrients than one with everything trimmed low and neat.

View attachment 4512

Next week this one will be low and neat while two more become just like it. So accumulation and uptake change dramatically, impossible to monitor much less target. Totals for the week are a known constant, an accurate number easy to go up or down from
Okay.
Totals for the week are 18/6/24 and .45 Fe. Thats for whole tank volume with 50% water changes
Lastly, do you find dry dosing or making a solution is easier?
 
I like solutions because there's less measuring out to do. Its not so bad with just a tank or two but with four 75s four 20s a 40 and a 50...having one solution is definitely easier!
Makes sense, those squeeze bottles would make it easier as well. Cool, I give your numbers a try, doble dose after water change then 2 more times throughout the week.
 
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