Just like to add an update as to where I'm at after 3 weeks.
The tank seems to have turned the corner and is back on track. I've been doing multiple smaller water changes and extra filter cleans which seems to have helped. Lights also dimmed 9%.
Fertilizer wise I stopped dosing Urea and thought I was adding this level of nutrients to the tank.
I think I get it now (had to look back through the thread). Please correct me.
1) Tank was healthy (under EI)
2) You dosed this:
This is what I was dosing when it went Pete tong.
N03 8.8ppm
N 0.65ppm (from urea)
P04 1.19ppm
K 6ppm
Mg 0.4ppm
Fe Edta 0.4ppm & Fe dtpa 0.05
3) Then you dose this:
Came to make a new mix up tonight and realised I've only been adding 75ml of macro solution instead of 100ml p/w and 75ml of micro instead of 90ml. So I've actually been adding.
No3 8.7ppm
P04 2.18ppm
K 6.39ppm
Mg 0.74ppm
Fe 0.25ppm (from csm+b)
Fe 0.09ppm Dtpa
Not exactly lean dosing but thought it might be of interest.
And dimmed the lights down. + small water change + small cleans on filter
4) Largest changes:
Biggest changes from 3 weeks ago are no Urea and the P04 increase and overall Mg increase. N, Fe and traces have actually reduced.
5) Tank gets better
*** Looks like gravel with root tabs? Can I assume you have active substrate. And of course, CO2 injection.
We want to know why.
Contingent on my assumptions above, let's try to figure it out!
This is not so simple. LOL.
Let's put some thoughts to get the juices flowing;
1) Urea is not magic. It provides Ammonia and CO2. But the plant does need some nitrate and if we force the plant to take too much urea and don't provide the nitrate the plant needs to convert it and spend CO2. Deficiency. Ok. Bacteria can take the excess urea and convert to nitrate for us. This can be bottlenecked by oxygen and/or abundance of species. Time will fix abundance, when oxygen is abundant.
If you had abundant, rich substrate at the time, I reckon increasing your light and potentially CO2 in conjunction - while maintaining appropriate flow - would actually have saved your system due to increase O2 evolution and excess energy availability for the plant to promote nutrient motion from the roots to the shoots! Alternatively, nitrate in the column MAY have helped while leaving light alone.
2) Your tank went south after that Urea dosing stuff up top. You had higher micro and less PO4. It is possible that increasing PO4 may have helped your tank in situation above. I can't remember:
Did you see brownish/black algae or did you see green algae when it went south. If blackish/brown, then intuition suggests leaning towards biological immaturity to handle the change in nutrients. If greenish, leaning towards NO3 and PO4 to "fix" the issue. You see, PO4 is important for energy as well -- ATP -- so if we had any new tissue and any shortfall OR we needed to synthesize more ATP for the roots to be able to pull up nutrients, then it needs to be there, AND PO4 very important for root developement so if the plant is trying to respond to get more of something from substrate and/or create more roots it needs PO4 to grow those roots.
3) If you have rich substrate, you need light since - don't remember but can gather - some nutrient movement requires energy so we need to give the plant as much energy as it needs via light. Or you need to feed it in the column and force feed it without the cost of energy. BUT I know that nutrient transport through Xylem does NOT require energy (when there is water and in terrestrial plants) -- I think
@dw1305 will know if nutrient motion from roots to shoots in aquatic plants requires energy or not. I'd be shocked if it was entirely free, but not sure. If the plant wants more roots, it will have to build the tissue though and I think that's where 2) comes in.
4) So you increase PO4, pull off the urea, rest is kind of the same. Small frequent water changes. Light dim. Not sure we need to dim the light. Small frequent water changes means you are constantly resetting the balance to facilitate consistent nutrient acquisition --> gives plants time to adapt to stability. Less urea = less demand on nitrate (which we explain above how we can get it from roots or leaves) and also bacteria (which we explain above) sending the system out foi whack.
So the fix entailed
1) more energy potential (or root dev. to facilitate substrate acquisition) via PO4 +
2) less demand on systemic N via less urea +
3) more WC keeping it in the same "state" to allow predictable adaptibility for the plant and more cleaning of filtration for distribution/less ammonia strain and oxygen demand from clogging etc and bacterial use +
4) a very minor decrease in light (put it back up let's see what happens) --
could play into 7) below bringing it back to reducing demand CONTINGENT on the water column giving it what it needs instead of pulling it from substrate +
5) time for bacteria to grow +
6) less micros ... a potential to make them not the thing that drives the demand via leidbig and also make the water chemistry "less crazay"
7) You inreased Mg a potential to increase GH -- despite a small increase, your water is so soft that it is relatively large -- this could reduce the amount of nitrogen/phosphate in the column that gets "force fed" into the plant leaves -- reducing the demand on everything * ...
Hope that helps get us thinking. If more comes, I'll post.
I mean all of the fixes helped hone in the demand to achievable amounts ... I think? It seems clearer now: All of my “thinking this would have saved the system” are actually what you ended up doing whether directly or indirectly.
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