Low Tech Fertiliser Dosing. Whats your technique?

[MichaelJ]

Without wishing to speak for him, I believe Darrel uses the 'pinch or dip' technique with dry salts

This is hilarious...well @Wookii, lets see what Darrel says here:

At the moment my fertiliser regime is <"pretty ad hoc."> for both magnesium (Mg) and iron (Fe), and consists of a small slosh of <"very pale blue Miracle-Gro">

A small slosh ... I love this 🙂 A slosh is similar to a slop which is close to a splash which is widely recognized to be just about 5.91 ml. I suppose a small slosh would be around 3 ml... - hard to say if thats a lot for a 70 L low-tech tank, but we do not have enough information to work out the ppm's.

When I run out of "Miracle Gro" I've bought a kilo of <"Solufeed 2 : 1 : 4 mix">. When I start with the <"Solufeed"> I'll work out what gives me 10 ppm nitrogen (N) (and ~44.3 ppm NO3 equivalent)

Now, 10 ppm of N, that was worked out fairly painstakingly... Again, a lot for a low-tech! I am curious about the rationale for that high level of Nitrogen, but I suppose that the occasional dosing will have to make up for a pretty long run.

and dilute that <"in a milk carton (6 pints of water)"> to see how blue that looks.

So the blue color comes from a dye that is used in terrestrial fertilizers to enable the user (applicator) to see what has and hasn't been fertilized and how even the distribution is. It can also be used to gauge the concentration of the fertilizer when diluted into a liquid - see below:

Then I just need to ensure that the water I add to the tank is always less blue than my trial run.

Sounds pretty slipshod, but in reality its probably accurate enough if your memory for color is good 🙂

Also I haven't tested conductivity recently, I've just observed <"the snail shells">.

An here comes... wait for it... The Snail Shell index...!

Without wishing to speak for him, I believe Darrel uses the 'pinch or dip' technique with dry salts using complex mammalian opposable digits - not a gram scale in sight!

Perhaps the message here is that we too often waste our time getting too caught up in measuring things out to the last digit on our microgram scales? 😉

Cheers,
Michael

This is the best forum ever. You could spend days here reading there is just so much to digest. I have so many bookmarked posts the list now runs into pages. I think I need a computer just dedicated to these articles.

Dirk

I very much agree... What sets UKAPS apart is the excellent signal to noise ratio... While other forums may have a lot more members, and thus posts, you will have to dig through a lot more less relevant posts (noise) to find the good information (signal).

Cheers,
Michael

 

[dw1305]

Hi all,

Now, 10 ppm of N, that was worked out fairly painstakingly... Again, a lot for a low-tech! I am curious about the rationale for that high level of Nitrogen, but I suppose that the occasional dosing will have to make up for a pretty long run.

I don't pour in the whole six pints, just an amount (again unspecified) and it is occasional dosing.

For the home tanks on Saturday morning, when I'm watering / feeding the house plants (and containerised Blueberries, Azaleas etc) I'll look a the tanks, if the Frogbit looks a bit pale the tank gets a slosh of fertiliser, if it looks hale and hearty? It doesn't.

Perhaps the message here is that we too often waste our time getting too caught up in measuring things out to the last digit on our microgram scales?

Agreed, but it is slightly different for me. I've kept tanks for a long time, I have no interest in optimal growth (or aesthetics or "rare" plants) and plants have been both my day job (and my amateur interest) since I was in my teens.

cheers Darrel

 

[kayjo]

What does the "Duckweed index" indicate when the floating plans are thriving, but all the submerged plants still are unhealthy and dying?

 

[si walker]

Wow. This has been my best post so far!
I new that there would be many hidden tips that people do daily and others can learn from. The idea of reading the plants, duckweed or stems is really fascinating.
Keeping a LT tank in a LTech way is whats interesting.
I now need to start looking into those other plants that can be used as floaters and also TDS Meter.
AMAZING replies.
Keep em coming if its helpful.
Thanks all.
Simon

 

[MichaelJ]

I don't pour in the whole six pints, just an amount (again unspecified) and it is occasional dosing.

Yes, I got that part wrong. Sorry.

What does the "Duckweed index" indicate when the floating plans are thriving, but all the submerged plants still are unhealthy and dying?

Hi @kayjo, I have not experienced this myself, but in my case I used it only in low-tech tanks with easy plants. I suppose it depends on what type of plants we are talking about, and if this a low- or high tech tank, what the state your tank is in etc.. If this is a current problem in your tank, I suggest you post the issue in the Plant Help section and post some pictures with additional tank details, so we can see what the situation is.

Cheers,
Michael

 

[John q]

What does the "Duckweed index" indicate when the floating plans are thriving, but all the submerged plants still are unhealthy and dying?

For me it would indicate that the issues aren't nutrient related, at least not lack of nutrients.
I used this method when reducing my dosing and when a noticed issues with the frogbit I knew I'd reduced the fertiliser to much.

Frogbits a good canary for "nutrient" deduction, it isn't starved of C02, so that can be ruled out, and it gets first dibs of any light, again taking lack of light out of the equation.

 

[The Miniaturist]

It could be the nutrients are borderline sufficient so the frogbit, having access to plenty of CO2, is using most of them & starving the plants beneath it. Also shading them too much if the light is low.

As @MichaelJ said, put the question in Plant Help & you'll get a load of help.

 

[Tim Harrison]

It could be the nutrients are borderline sufficient so the frogbit, having access to plenty of CO2, is using most of them & starving the plants beneath it. Also shading them too much if the light is low.

I don’t think it works that way. Having access to atmospheric CO2 means floating plants react quicker to changing nutrient status. Thus observing leaf colour and dosing when appropriate means any potential deficiency is avoided before it becomes an issue for submersed plants

 

[MichaelJ]

I don’t think it works that way. Having access to atmospheric CO2 means floating plants react quicker to changing nutrient status. Thus any potential deficiency is avoided before it becomes an issue for submersed plants

Hi Tim, Generally I would say it works, but I am torn on the corner-cases. I could see the floaters being unlimited on CO2/light, as they are, potentially could be starving off the plants underneath if the tank is tethering on nutrient deficiencies. Some reports that Frogbit are quite greedy when it comes to Nitrogen especially - so if you have a lot of floating plants that could be an issue. Again, I think the type of submerged plants have to be factored in as well. You might think you are adding enough nutrients, but the submerged plants might have a hard time with uptake due to other water parameters / conditions.

Cheers,
Michael

 

[Tim Harrison]

It’s an indicator and it works very well when applied with common sense.

 

[dw1305]

Hi all,

What does the "Duckweed index" indicate when the floating plans are thriving, but all the submerged plants still are unhealthy and dying?

What @John q says, either lack of light or lack of CO2.

cheers Darrel

 

[jaypeecee]

Hi @dw1305

Having never used the Duckweed Index to any meaningful extent, what are the implications for submersed plants as regards lighting intensity? Floating plants will obviously receive more light than submersed plants and floating plants receive the same spectrum as that being emitted by the light(s). But, underwater plants will see things differently. Or, am I missing a trick?

JPC

 

[dw1305]

Hi all,

Floating plants will obviously receive more light than submersed plants and floating plants receive the same spectrum as that being emitted by the light(s). But, underwater plants will see things differently. Or, am I missing a trick?

I assume it is just a PAR effect. The bottoms of all my tanks are pretty gloomy, and just tend to have Aroids, ferns and mosses.

cheers Darrel

 

[_Maq_]

What does the "Duckweed index" indicate when the floating plans are thriving, but all the submerged plants still are unhealthy and dying?

either lack of light or lack of CO2.

1. lack of light - yes
2. lack of CO2 - no
3. lack of oxygen
4. elevated dissolved organic compounds in the water column
5. high oxygen demand in the substrate, i.e. too much easily degradable particulate organics in the substrate.
I oxygenate water permanently, so I keep CO2 always low but not missing altogether. Growth is much slower compared to CO2 enhanced tanks, but I don't believe any true submerged plant suffers from low (i.e. normal, in fact) level of CO2.
There are always growth supporting and killing factors at play simultaneously. CO2 injection is growth supporting, so it helps plants to overcome other, killing factors' effects. I prefer the other way - eliminating the killing factors (see above the list). Normal level of CO2 seems to be no problem.

 

[Wookii]

2. lack of CO2 - no

Of course it can indicate a lack of CO2? We’re not talking a high tech CO2 injected tank here, we’re talking a low tech one.

A low tech tank requires good surface agitation to optimise gas exchange both of O2 and CO2 - both come hand in hand.

It’s very easy for areas of a low tech tank to be devoid of dissolved CO2 unless that water is regularly replaced with water from the surface which is at equilibrium with atmospheric levels of CO2, simply because levels are so low to start with. You are doing exactly that here:

I oxygenate water permanently, so I keep CO2 always low but not missing altogether.

You are not keeping CO2 low by doing that (in the context of a low tech tank), you are keeping CO2 as high as it can be in a low tech tank, by ensuring that CO2 loaded water at the surface is mixed with the rest of the tank.

 

[_Maq_]

you are keeping CO2 as high as it can be in a low tech tank, by ensuring that CO2 loaded water at the surface is mixed with the rest of the tank.

Am I? Apart from the plants, tanks are usually net CO2 producers.

 

[Wookii]

Am I? Apart from the plants, tanks are usually net CO2 producers.

True, but not nearly at the rates that plants consume it, and no way near as much as can be introduced by good surface gas exchange.

 

[dw1305]

Hi all,

Am I? Apart from the plants, tanks are usually net CO2 producers.

I think the point is that you can' t take plants out of the equation, they are massively both net oxygen producers and CO2 consumers.

Cheers Darrel

 

[_Maq_]

Hi all,
I think the point is that you can' t take plants out of the equation

They are CO2 consumers, during daylight. So, the question is, whether fish and microbes provide them more CO2 than oxygenation? @Wookii took for granted that oxygenation makes the water saturated with CO2 as much as possible. While I believe that this is not the case, except in the afternoon, perhaps.
In other words, if I didn't oxygenate, CO2 level would be higher than 0.5 ppm during night and earlier half of the day.

 

[John q]

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In other words, if I didn't oxygenate, CO2 level would be higher than 0.5 ppm during night and earlier half of the day.

@_Maq_ you seem like an educated guy, other than being argumentative and splitting hairs, perhaps you could show us the fruits of your labour's.

I for one think I can attain some knowledge from you, but you need to show us your onions 😀