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The levers of a balanced low energy tank

Hi all, Light is definitely the driver of everything else, but you can always control light intensity, even when you can't control light intensity with a dimmer, by adding floating plants, as a <"net curtain">. Personally I like a long photoperiod and a reasonably bright light.

Floating plants eliminate CO2 availability from the equation and they are plants adapted to <"intense sunlight on Varzea lakes etc">. So you have also taken light out of the equation (unless your light is so dim on full power that not even floating plants receive enough PAR to grow).

That just leaves the <"fourteen mineral nutrients essential for plant growth">, and that is where your floating plants come in useful again, via the <"Duckweed Index">.

It isn't very exciting as an approach, but by isolating each of the separate factors;
  • Light,
  • CO2,
  • Nutrients.
It allows you to eliminate them one at a time when you are problem solving. If you have a bright light and your floating plants are
  • yellow,
  • have stunted leaves or
  • don't grow at all,
<"it is a nutrient issue">.

If you floating plants have yellow stunted new leaves, it is a problem with a <"non plant mobile nutrient"> and you need to wait a little while for an improvement in plant growth to occur.

For the plant mobile nutrients as soon as you've added the nutrient limiting plant growth you should see a difference. With nitrogen the greening effect can be observed with in minutes for many plants, they visibly go greener as you look at them.

cheers Darrel
But wouldn’t floating plants reduce the ‘window’ of the tank so to speak reducing the effectiveness of gas exchange? In this case you would also be altering another one of those levers.
 
Hi all,
But wouldn’t floating plants reduce the ‘window’ of the tank so to speak reducing the effectiveness of gas exchange? In this case you would also be altering another one of those levers.
They will to some degree, but it isn't a straight forward case of "30% cover = 30% less oxygen", leaf architecture will matter, as will radial oxygen loss etc.

cheers Darrel
 
One thing I’ve noticed whilst experimenting (loosely) over the last few years with my soft water tank is how plants adapt to co2 levels.

We talked about the RUBISCO enzyme many times here over the years on UKAPS and I find that this enzyme is often the key to understanding how plants behave. For the record I have injected co2 in the past though I no longer do this. I don’t dose fertilisers and change water infrequently with soft Manchester rain water.

This tank (for the time being) is able to support duckweed at a TDS of 160ppm. If I pop in a couple of algae wafers during the week it goes mental indicating that nutrients are limiting growth.

during this time whilst I had regular surface coverings of duckweed I knew light, co2 and nutrients were not an issue for this plant yet my crypts were growing slow. This is because I was running an airstone. What I noticed each time I switched back to my trickling overflow filter for a few weeks then back to my airstone was that in each case the leaves that had been growing under each method were rejected and collected algae in addition to that the first new leaves following each switch were small, twisted and pale but the next leaves got progressively better until the plant grew just fine.

Though healthy, plants under the airstone method grew painfully slow and so was their transition to lower levels of co2. But after numerous weeks they would be ok. I assumed that as the leaves grew larger they would capture more co2 and an exponential growth rate would ensue that would see the plants grow fairly rapidly after a while. Growth did speed up but it was still very slow.

the transition under the ‘slow trickle waterfall effect’ was much faster and growth was faster but initial new leaves would always appear stunted. Again, after a while they would grow very well.

The good thing about these methods in my opinion is that once running, co2 levels remain relatively stable 24/7 allowing the plants to transition perfectly well. But you needed to be patient.

It made me think about how difficult it can be to keep co2 stable in high tech settings. Yes they grow quickly, and they transition quickly (alter rubisco enzyme content) but they still fail to produce the perfect leaf the first time around. It made me think that more often than not leaf issues are rarely nutrient issues (how can they be if dosing EI) but rather plants constantly responding to unstable co2 levels and new diurnal cycles.

just some observations.
 
The good thing about these methods in my opinion is that once running, co2 levels remain relatively stable 24/7 allowing the plants to transition perfectly well. But you needed to be patient.
I think that's where a lot of new high tech scapers may fall into chasing ghosts. Co2 injection is an inherently unstable practice and a dynamic situation as surface agitation and plant mass changes. The plants are constantly trying to adapt which then leads to people making further unnecessary changes to other parameters without waiting enough time to see what difference the last change made.
 
I think that's where a lot of new high tech scapers may fall into chasing ghosts. Co2 injection is an inherently unstable practice and a dynamic situation as surface agitation and plant mass changes. The plants are constantly trying to adapt which then leads to people making further unnecessary changes to other parameters without waiting enough time to see what difference the last change made.

ultimately I personally believe this is it. I honestly believe plants can grow on much less nutrients than we think. It is the co2 thats hard to ‘get right’ and is what causes most algae issues and apparent stunted and deficient leaves.

It makes sense that seasonally submerged macrophytes be extra ‘sensitive’ to this parameter as essentially it’s make or break when they are flooded.
 
It is the co2 thats hard to ‘get right’
Trying to dissolve a gas that constantly wants to get out of a warm environment and keep it stable is like herding cats. Errors with nutrients is far more forgiving unless they are combined with gas issues. The tank I have sometimes I dose like clockwork but there's times when I've just let it go through laziness and being busy. At worst a few plants look a bit ropey. When I was weaning it off co2 to go back to low tech, even when as gradual as I could it was a total disaster.

I was looking at setting up a cube tank at the start of summer so put a nice root into the cube and filled it with tap water so the root would sink when I finally set it up. In the end up I didn't get round to setting the tank up, there must have been some dried up plant matter on the root and after about 3 months I had moss growing on the root, a small java and duckweed floating on the surface. :D
 
Just for clarification, I have never changed any water in that cube, added any frets and the only light it gets is from a window but compared to being stuck to a dry bit of wood in a cupboard that's luxury. But then I see someone with a High tech tank wondering why their moss keeps dying :shh: I suppose that doesn't sell lights, ferts and co2 regs though so don't tell anybody :)
I think what I'm trying to get at is when changing co2 levels the the plants need to be in Good health in much the same way as an an athlete needs to be at the top of their game before entering a competition. Makes No sense going into a sprint competition if you have a bit of a cold to start with. Yes been drinking :p
 
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Just for clarification, I have never changed any water in that cube, added any frets and the only light it gets is from a window but compared to being stuck to a dry bit of wood in a cupboard that's luxury. But then I see someone with a High tech tank wondering why their moss keeps dying :shh: I suppose that doesn't sell lights, ferts and co2 regs though so don't tell anybody :)
I think what I'm trying to get at is when changing co2 levels the the plants need to be in Good health in much the same way as an an athlete needs to be at the top of their game before entering a competition. Makes No sense going into a sprint competition if you have a bit of a cold to start with. Yes been drinking :p

I think it’s just one of those where the plant is just trying to adapt all the time. Another reason I think the bell method of co2 delivery is more stable. In that San Francisco shop Ocean aquatics/aquariums he says he put root fertilisers in once a year. He has relatively dim lighting in most tanks too but you can clearly see just how much plant mass the annual fert tabs support. Not to mention all of his emersed growth.

his fish do seem to breathe quite rapidly in some tanks though.
 
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