Help Help me with fertilizer recipe please

[Art]

But theres something important about having a certain concentration present. Probably realted to nutrient interactions or the +/- balance of ions

Always reminded that we know a lot now-a-days about keeping plants, but there are still mysteries that just work.

 

[Burr740]

Always reminded that we know a lot now-a-days about keeping plants, but there are still mysteries that just work.

Yeah we're way above my pay grade now but somebody could explain it. There is active absorption and passive absorption. A lot of it is just +/- ions pushing/pulling against each other, plants themselves having a slight negative charge inside

In simple terms we can just say there needs to be 30 ppm of Ca in the water for plants to be able to get the 2-3 that they need. Sorta like a co2 diffuser that needs 35 psi to crack it. Thats a very loose analogy but somewhat paints the picture. And of course the concentration of all the other nutrients and their respective charge strongly affects what actually gets in the plant

 

[Marwen]

I think those numbers are about right

Mg is a little high, or to put it differently you dont need that much ime. My tap comes with 30-35 ppm Ca and 4-6 Mg. Its what Ive always used in all the tanks. Ive spent long periods of time running different levels of Mg, all the way up to 20 down to just whats in the tap. And this is with anywhere from 6 to 12 tanks going at the same time, some sand, some soil, different KH, etc

I never noticed anything specifically that adding more helps. And up in the 15-20 range plants seem to have a harder time getting enough K. This would coincide with Mulders chart and Ive seen it happen first hand, repeatable. I cruised at around 10 for a few years by adding an extra 5

About a year and a half ago I stopped adding any extra, just the 4-6 from tap along with the 30-35 Ca. Plant growth across the board has never been better. Not that lower Mg helps anything just the point that more isnt needed. We've all seen the crop studies with the 3:1-2:1 ratios. Thats why I started adding it to begin with 12 years ago like so many other hobbyists

But Ive found more often than not these ideal ratios from crop studies dont always apply to our underwater plants. Fe:Mn is another example. Personally with Mg I would err on the low side because it really doesnt matter and too much can start affecting other nutrients

In your case with 22 ppm Ca Id just go with the 4 thats in your tap. Also you may want to raise Ca into the low 30s. 22 might be enough but quite a few plants will do better with more, Rotala sunset and Florida come to mind, downoi, AR

About your water change dosing question. Youre exactly right and thats why daily dosing, especially macros, is not ideal if youre doing more than say 25-30% water changes. Because like you said its a big drop and takes a long time to catch back up in daily dribbles

Even with 50% I like to dose extra macros right after then a couple smaller doses through the week. Say 50% of the weekly total post wc, then 2x 25% through the week. If youre set on daily with an autodoser Id make a solution (or dry dose) to add about 50% of the weeks total after the water change, then you can daily the rest of it out in equal doses. That'll be a much more consistent water column

This is all just my personal phylosophy based on my own anecdotal experiences and what happens in my tanks. Others may have a different opinion or experiences

@Burr740 I actually played a lot with Ca/Mg levels in my RODI water and my experience definitely agrees with yours. These are my beliefs now based on my anecdotal experience of changing levels and observing plants for weeks every time:

• 15 ppm Ca is pretty much non-limiting. I've gone as low as 12 ppm without issues. And I tried 30 ppm without issues either. People who say shrimp need 30-35 ppm? Maybe. I don't know much about shrimp keeping. I just know that my neocaridinias were fine and breeding at 15 ppm. I now stick with 20 ppm and never think about Ca again.
  
  
• I suspect that there is some kind of relationship with micros, like you can afford to go a bit leaner with them when Ca is lower (say 15 instead of 30-40 ppm Ca) without stunting. And vice versa: you can go a bit higher more safely when Ca is higher without stunting. When I did 12 ppm Ca for a couple of months, it was easier to stunt some plants from too much micros. But lowering them fixed it. Also some species like Pogostemon deccanensis (aka erectus) grew more readily like weeds under lower Ca/micros. I was able to adapt them to higher, but less readily so. Just my observations.
  
  
• Mg I tried from 6 to 14 ppm. No difference either. Macrandras seemed to do a bit nicer at higher Mg. But that could be for other reasons. So now I do 10 ppm Mg and just forget about this.
  
  
• Ca:Mg ratios from 1:1 to 4:1 made ZERO difference. So I don't get how many hobbyists and GH product manufacturers say 3:1/4:1 is what's "optimal". I thought that came from crops research but nope. I've consolidated the best research papers on this ratio and the scientific consensus clearly agrees that this ratio has absolutely no impact and that it's rather the individual ppms and whether they are limiting that matters. Unless we go to crazy ranges (say 40:1, 1:25, or whatever) where we start to see things like antagonism issues, Mg toxicity, etc. So 1:1 and 2:1 (like my 20:10ppm Ca:Mg) are also perfectly fine when remineralizing RO water IME and will grow everything.
  
  
• The K:Ca:Mg ratios some people claim are optimal also seem unfounded (as long as we avoid crazy unbalanced ranges). K-wise, All I've found for sure is that, under high energy conditions with very high CO2 and strong PAR, K is best kept high. With my 40 ppm CO2 I keep it at 35 ppm. I tried keeping it at the same level as NO3 (in the neighborhood of 15 ppm) and lower and ran into issues. BUT, when I tried this in my low energy 10-15 ppm'ish CO2 tank, it worked. Somehow, lower macros that did NOT work in my main tank, worked fine there. I find that somehow the combination of very high CO2 with strong light signals to the plants to grow fast, and if they don't find enough macros, they struggle and so algae thrives. Interestingly, a few select plant species were an exception and did fine with this (very high CO2 + lean macros), but most and the tank as a whole definitely struggled. But when you adapt them to low CO2/light, suddenly the lean dosing folk's formulas start to work fine. This has explained so many contradicting experiences for me lately. And it does make sense since (after light) CO2 drives everything else.
  
  Next time someone says their tank is thriving with 4 ppm K dosing per week, I'll have a pretty good guess about their true CO2 levels. And I'll be happy to dare them to reproduce it with my 40ppm+ CO2.

Also not everything can be dosed for consumption, NO3 and micros probably the only ones. Plants arent eating through 30 ppm of Ca in a week, or K or even PO4. I had icp done one time by a friend who can do it at work. Post water change, mid week and weeks end, Ca barely moved a couple ppm

But theres something important about having a certain concentration present. Probably realted to nutrient interactions or the +/- balance of ions

Also very true.

Just because plants would consume, say, a maximum of 2 ppm Ca per week doesn't mean that having that in our tanks would be non-limiting. Better to have 10+ times that concentration so plants don't have to look far for those ions.

For me, an analogy would be growing a tree in a pot at home versus it growing in nature. Some people might say why fertilize so regularly when in nature there is no fertilizer? In nature, the tree will send roots in soil freely looking for whatever it needs. Not to mention that it will have access to things like symbiotic fungal networks and all kinds of complex interconnected life. The pot we have it in at home is pathetic in comparison, so we better feed it in what might appear as more than what's natural but really kinda isn't.

 

[Burr740]

@Marwen Ive also noticed a couple specific things you said

Pogo erectus doesnt toloerate high micros very well. In fact it was one of my early indicator plants when I started working on the custom mix. It'll stunt in heartbeat. Higher K seems to help, for whatever eason

There is such a thing as too much co2. The majority of my tanks have always been fishless, so back in the day my thinking was to run nose bleed levels of co2 to make sure that base was covered. Because a few years ago it was commonly accepted that co2 doesnt hurt anything and theres no such thing as too much. Much of the hobby still believes that

I think it came from whenever folks were having a problem with EI back in the day, it was always CO2, CO2, you need more better CO2

Ive spent a lot of time running 1.5+ drop, even up to a full 2. Things always went south with extreme levels. Id say much more than 1.4 or so will cause issues. This is tank dependent of course, many external factors come into play. These days I try to stay around 1.2 or so, with a solid 1 point by lights on. More than that tends to have negative returns...in my tanks

I believe like you said, it drives growth as much as light and probably more than ferts do. So it needs to stay within a balance too