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dry ferts in filterless tank ?

eminor

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Hello, if i put dry ferts in my filterless tank, does the powder will dissolve and propagate in all the tank or it will stay in the same area ? thx
 

_Maq_

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I wouldn't recommend that. But in principle, yes, salts would dissolve and spread thanks to diffusion - although I can hardly imagine any tank without any mass flow, which would accelerate spreading of the nutrients substantially.
 

dw1305

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Hi all,
Hello, if i put dry ferts in my filterless tank, does the powder will dissolve and propagate in all the tank or it will stay in the same area
What @_Maq_ says, it is like sugar in coffee, if you don't stir it, it will take a lot longer to go into solution, but eventually it will.

Once the "sugar" (fertiliser) is dissolved then it will spread through the tank, in the same way that all the coffe is sweet, you don't get bitter patches.

cheers Darrel
 

xZaiox

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But in principle, yes, salts would dissolve and spread thanks to diffusion
it will take a lot longer to go into solution, but eventually it will.
Does this imply that plants don't need flow to access dry salts? Or is the rate of diffusion slower than plant intake? High flow generally receives a lot of praise, so I'm curious about how necessary it is.
 

dw1305

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Hi all,
Does this imply that plants don't need flow to access dry salts? ............. High flow generally receives a lot of praise, so I'm curious about how necessary it is.
Flow isn't a deal breaker, but it certainly makes a difference. In my case I'm most interested in maintaining oxygen levels (in the filter), but flow will help redistribute CO2 and nutrients as well.

cheers Darrel
 

Hanuman

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Hi all,

What @_Maq_ says, it is like sugar in coffee, if you don't stir it, it will take a lot longer to go into solution, but eventually it will.

Once the "sugar" (fertiliser) is dissolved then it will spread through the tank, in the same way that all the coffe is sweet, you don't get bitter patches.

cheers Darrel
Not so sure about that. For the sugar example for instance if you don't stir it will eventually dissolve but will remain at the bottom of the cup since it's denser. Same goes with the tank and dry ferts. If there isn't any water movement whatsoever then the dissolved salt will remain mostly at the same spot and because it is denser than the water it will stay at the bottom.

@eminor If I where you I would dissolve the salt in some tank water then spread the concentrated solution in the tank.
 

_Maq_

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Does this imply that plants don't need flow to access dry salts?
Plants, both submerged and terrestrial, take up solely dissolved nutrients.
In roots, mass flow is very slow and diffusion is the main force of nutrients' dispersal.
In water column, water flow primarily helps to make so called diffusive boundary layer (DBL) thinner. DBL is the space surrounding all interfaces where mass flow is non-existent and solutes move solely thanks to diffusion. If it gets thinner thanks to rapid water flow, plants gain better/faster access to oxygen, carbon dioxide, and dissolved nutrients, and vice versa, while photosynthesizing, oxygen disperses more quickly from the leaves and the rate of photorespiration gets lower.
Water flow is a good thing, indeed. Thanks to water flow you can improve plants' access to CO2 without CO2 injection, par example.
 

dw1305

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Hi all,
If there isn't any water movement whatsoever then the dissolved salt will remain mostly at the same spot and because it is denser than the water it will stay at the bottom.
Definitely theoretically true, but I think because we are dealing with very dilute solutions, that the differences in density will be minimal.
In water column, water flow primarily helps to make so called diffusive boundary layer (DBL) thinner. DBL is the space surrounding all interfaces where mass flow is non-existent and solutes move solely thanks to diffusion. If it gets thinner thanks to rapid water flow, plants gain better/faster access to oxygen, carbon dioxide, and dissolved nutrients, and vice versa, while photosynthesizing, oxygen disperses more quickly from the leaves and the rate of photorespiration gets lower.
That one.

You can't see the nutrient ions, but you can see this effect, with dissolved gases, when you turn the filter off towards the end of the photo period and the plants start pearling. The plants were producing oxygen at the same rate before, but the locally dissolved oxygen saturated water was constantly being removed.

If you get pearling with the filter on? it just means the entire water column is saturated with dissolved oxygen.

cheers Darrel
 
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