Fertilizing the substrate

If you are careful and maintain good nutrients in the water column, generally there is no difference for most plants.

Simply having large roots does in no way suggest they prefer root uptake. These plants come from high flow regions such as streams and rivers that get scoured.
They need them to hang on and as well as when the water level goes down and they are exposed to air(no water nutrient sources available them!). So they have a ecological plan there, not a static environment......

I grow massive Crypts and sword plants without any sediment sources, they become very weedy. I suppose I could do a controlled study and take the before/after dry weights, but Cedergreen, Madsen 2002 already did this experiment for 4 weedy submersed aquatic plants, Crypts and swords are not really permanent submersed species in nature, thus are poor candidates for such generalizations.

Cedergreen and Madsen found even cutting the roots off had no change the the relative growth rates of the 4 species used vs the controls with roots.
So the roots really played little role when the water column is nutrient rich.

That's what is known and what is the research.....at least for those 4 species......

A better focus should be on the consistency of supply so applying the assumption that the plants can get the nutrients from BOTH source would be a wiser approach.

That covers both assumptions.

Unlike this "either or" business:thumbsdow

Another question is do you honestly want larger sword plants?
I don't.
Crypts? Generally not either.

I know these plants do well in both situations, but other plants need water column fertilization as it targets all plants well for most any scaping design one might have.

Still, adding ADA AS, or a sediment with good river clay/swamp soil and some sand can certainly add to the water column and adding ferts to the water column reduces the amount of nutrients required from the sediments as well, thus you get more out both than you do from "either or".

Less critical water column dosing and longer lasting sediment nutrient source.
This makes the assumption that some plants do prefer sediment uptake.
We really do not know this, but it's still a safe assumption given the trade offs.

Regards
Tom Barr

bowman said:

A simple observation of the growth of two Cryptocoryne balansae plants in my tank prompted me to look at the issue of substrate nutrients.

At the time of planting one of the Crypts had a clay nutrient tab inserted into the substrate at the root zone - the other did not.

After six weeks, the Crypt with the substrate nutrients has more leaves and longer leaves than the one without.

My crypts seem to like their nutrients both ways, thats why I posed the question about methods of dosing the substrate.

Also it may be an advantage to be able to at times target specific plants / parts of the tank for additional nutrients - rather than fertilizing the whole tank via the water column.

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So are you sure you had non limiting water column fertilizer during the 6 week's time frame? If not, then you really cannot say, the results would be confounded.

Some suggested in the past that adding ferts prevented algae, that's not true decidedly. However, it is convenient/easy and for some species, it might play a role. But there's strong arguments for it not being so also.

I've seen these same root preferred feeders grow to massive sizes rapidly in water column only fertilization.

I do not want more growth than that!
A 3ft Sword or a 3ft Crypt is not generally what I seek.
Amazon swords and C balansae both got that big in 6-12 months and had to be removed from a 24" deep tank with plain sand.

You need more growth than this?

Or was it more to do with your water column dosing routine?

Regards,
Tom Barr

Thanks everyone for your input.

I should point out that my interest in substrate fertilization arose not from an interest in growing massive Crypts, or any other oversized plant for that matter, but rather from the frustration of algal outbreaks.

I understand that to limit the conditions that favour algae,I need to achieve a certain balance between light, CO2 and nutrients/trace elements.

That, I have yet to achieve, but I am working on it.

I initially suffered a hair algae problem which is receeding, and am now dealing with some staghorn algae (among the hairgrass & I'm spot dosing with Excel).

My thinking was that if I am able to reduce the nutrients in the water column (where they are available to both plants and algae) and increase them in the substrate where they are available to plant roots, then I could achieve strong plant growth while limiting the nutrients available to algae.
Which is why I was enquiring about liquid ferts leaching out of the substrate.

That appears to me to be a reasonable strategy to explore, but I am a newbie so I am happy to stand corrected if this is a misconception.

Cheers

aquanut415 said:

i should add though after rereading the question...most people who do substrate fertilization don't use LIQUID ferts for the substrate, they use some kind of dry fert stick.

ada actually sells a liquid fert delivery system that you plumb into the substrate.. doesn't seem to be popular at all. ive never used it either.

ada also sells dry fert sticks for substrate fertilization... and a very expensice device to poke the sticks into the substrate.

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I have tried using dry fert sticks marketed for ferns and foliage plants in the substrate, and am monitoring plant growth and phosphate/nitrate levels.

An interesting observation with fert sticks.

Prior to setting up my tank I had received and collected some plants and to house them temporarily I planted them in small pots and housed them in plastic tubs.

A few weeks later when I planted my tank I noticed that most, if not all of the plants had considerable root growth in and around the fert spike.

Clearly the plants were taking advantage of substrate nutrients.

Current fertilizing orthodoxy is centred on the water column, but I suspect I am going to have some fun (and possibly reward) by mucking around in the substrate.

bowman said:

Thanks everyone for your input.

I should point out that my interest in substrate fertilization arose not from an interest in growing massive Crypts, or any other oversized plant for that matter, but rather from the frustration of algal outbreaks.

My thinking was that if I am able to reduce the nutrients in the water column (where they are available to both plants and algae) and increase them in the substrate where they are available to plant roots, then I could achieve strong plant growth while limiting the nutrients available to algae.
Which is why I was enquiring about liquid ferts leaching out of the substrate.

That appears to me to be a reasonable strategy to explore, but I am a newbie so I am happy to stand corrected if this is a misconception.

Cheers

Click to expand...

It's not, sounds good, but it is......... Baloneyious maxmius

Your algae issues have nothing to do with nutrients availability to the algae.
The problem is that you are not focusing on plant growth, grow the plants well, then you no longer have algae.

It's that simple.

Until you do, you will continue to have algae issues.
Plants define the balance, not nutrients.

Old wives tales, myths etc etc, a bandwagon of "me too's" suggest algae is caused by "excess" nutrients.

This same bunch never gives us any details about the test to show their claims, they never define what excess is and at what concentration, what CO2 or light level the algae are induce by, they rarely repeat the experiment and lack the control to consistently produce an algae free plant tank. Never seen one define plant biomass. I've seen the same banter repeated for 12 years on the web now. It's male Bovine manure. Research also agrues decisively against it as well.

Focus on growing the plants, not outwitting algae. You are getting side tracked here. You need to focus on mastering how to grow plants underwater.

This will help you a great deal.
Be specific about what species of algae you have, they suggest the environmental issue, and make sure you are consistent in the routines for dosing.

It's not hard.
It's just many folks make assumptions that are wrong and poorly thought out, even though we all start with good intent.

A good start for a plant tank is key to success.

You have not done this from the sounds of it.
We all make mistakes, just do not repeat them

Regards,
Tom Barr

I have tried the substrate fert proccess my self. I only used the fert while starting new plants and germinating the seedlings. I have used 6" plastic bins with perferated lids and screen over the holes. This helps to keep out the bugs. I have grown in nurseries and in my basements for years. Once the plants are going fine, I then would transplant them into tanks of verious sizes. I have used liquids with water changes, experimented with canister filtration and let the plants cycle like a natural eco system, thus building its own peat layers as well. I always remove water when adding new plants and just plug them like a rice paddy, then replace the same water back into the tanks.
I Also have used liquide ferts with no problems, trim the plants, only fert once a month with minimal amounts. The sand tanks does just fine and has mostly tall plants and no plants on the bottom, like shrubs in your yard. I have not kept a tank with a mossy bottom or the use of short hair grasses.
I guess ther is always a first time to grow a golf coarse for the shrimp farm.:icon_eek:

Maximo

I would like to add something and hopefully revive this conversation. I will try to be objective and provide enough information to assist anyone in helping me along. I also am having problems in the fertilization area.

Everytime I experience great plant growth it is accompanied by great algae growth, namely bba and staghorn. Even though I attempt to control the infestation with peroxide treatments or excel I ultimately end up tearing the tank down, doing a couple complete water changes, scrubing all equipment and bleaching the 90 + plants that go in the tank.

I am trying my best to get behind the nutrient excess logic. The same logic that the experts preach and EI dosing endorses but... everytime I dose at or above what my plants require I receive an algae outbreak that seems uncontainable. As much as I hate to admit it I was about to take the same perspective as bowman. My thoughts were I am dosing the water column which just BEGS algae to show up.

I guess the one aspect of dosing fertilizer that I don't think I am taking into account is fish load. There are tons of guides to dosing whether it be using blends, liquids, or dry ferts but none that take into account the bioload. This brings me to a single question:

What would be the differences in dosing amounts/schedules on identical tanks that had the same plant biomass but one had a significant fish load and one did not?

I can't help but think this is where I could be continually going wrong and end up tearing down my tank in disappointment because I can't control the algae.

Abrium said:

ok OS, I'm going to roll with you, I hope your right. I'm tired of the stuff.

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For whatever it's worth, I read somewhere that the key to combating algae early is plantings heavily -- very heavily -- from day one with fast growing plants. Do that even if they aren't necessarily the plants you want in the tank long term, but let them start your tank out so that they can just grow grow grow and help prevent any algae.

I took that idea, along with a sensible approach to fertilization (erring on the side of under-fertilizing rather than worrying about reaching a specific target and risking overdoing it) and I've had tremendous success so far. This tank is about 6 weeks old or so, has seen great growth and houses 16 small fish. Not a spec of algae has been seen so far except a couple leaves that came with it, which my otos munched up.

I started with an extensive amount of easy and fast growing stems: wysteria, cabomba, moneywort, and rotala. I also started with a pot of crypt lutea and bronze wendtii each which I spread over the tank. Over time the goal is to slowly swap out a lot of the stems for other plants, but in the meantime they've done wonders with establishing this tank and keeping it clean and look pretty good to boot! I've already had to trim the stems more than once, throwing away a fair amount. I've also had to thin the lutea and wendtii a bit as well to make room for a few of the other plants that are in there now.