# Possibly too much Osmocote?



## ForestDave (22 Mar 2021)

Hi.
I got a bargain price on 5 bags of Dennerle Scapers soil, but after reading a few reviews questioning the amount of nutrients in it  I probably stupidly thought I'd try sprinkling what I believed was a tiny amount of Osmocote underneath my Dennerle Scapers soil when I built my scape. I think it was about 19g worth over a 100x40cm base judging by the weight difference between the 2 packs I had delivered.  It hasn't been helped by the fact that I did a re-scape after 1 week as some things didn't go to plan and some of the Osmocote was probably brought higher up in the substrate. The tank is looking ok but most of the stem plants are struggling to put down good roots and are sometimes rotting away in the substrate. They continue to grow but very slowly, getting their nutrients from the leaves I presume. Indian Swampweed is living up to its name and seems happy enough. Rotala sp Colorata is doing ok but the leaves are small. Most of the other stem plants seem to be stuck at the same height, or growing painfully slow.

I don't fancy another re-scape. If the plants tough it out for another 3-6 months, will the excess nutrients in the soil dissipate, and hopefully, could things improve from then on?

Tank 200L
4 weeks old although FX6 filter has been running for 2 months, (4 weeks with plants and no substrate).
Ammonia/Nitrite 0
Nitrate, 0ish. Pretty much running clear on the test with the very slightest pink hue if you strain your eyes.
KH 3-4
Tap/tank water 7.7ph
Dennerle Scapers soil
Mini Landscape Rocks
Temperature 23 degrees C
EI fertz, 40ml macro/micro on alternate days basic APF mix for the moment.
4ml of Glute
The only algae issue so far was some green thread algae spirogyra on some high-up weeping moss. I removed the moss so I could blackout and nutrient starve it separately and that is back in the tank. There have also been a few diatoms in the last few days when I switched to water changes every 3 days.
Lights are 2x 38w T5. for 6 hrs per day, for the moment. The front one has a reflector on it as my carpet plants needed more light.
Water changes were 50% every other day for the last 2 weeks and every day before that. Although as mentioned I've just switched to water changes every 3 days.

I had that feeling of dread when I was debating with myself whether to sprinkle the damn things in, I always seem to go heavy handed with these things. I killed a load of strawberries with them last year and should know better! 😭😄


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## Tropicaltanklover (29 Apr 2021)

Sorry, I don't have an answer to your query, but was wondering how things have progressed in the past 4 weeks.


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## ForestDave (1 May 2021)

Tropicaltanklover said:


> Sorry, I don't have an answer to your query, but was wondering how things have progressed in the past 4 weeks.


Hi.
There were a few more replies but they seem to have been deleted for some reason? Either way the general consensus was that it probably wasn't the Osmocote causing the problem, although it may have slightly been an issue at the start when the fast release element of it was being released. I think my main issues were probably lack of flow to some areas restricting the CO2, constantly tweaking the CO2, plants that were in crap condition when planted and a long period of water changes every other day which maybe didn't leave enough fertz in the water column. 
I removed the reflector soon after I wrote the above post as I started getting BBA and staghorn algae and think it was too much light for the new tank. I only added the reflector 2 or 3 weeks beforehand as I didn't think the carpet was getting enough light. I binned the hairgrass and HC and opted for Marsilea hirsuita which is much easier to look after. I'm down to 5hrs light a day and decided I'd keep the fertz at the standard dose as I now do water changes twice a week. It's coming on, things are growing. I did a big cull of BBA ridden leaves and am going to lift the carpet and dunk it for 2 days in a 2x dose of glute. I'm putting another filter intake in the opposite back corner tomorrow, have tweaked the spraybar, and added a Jeboa SLW Sine wave powerhead in the middle to power up the flow a bit. My shrimp are happy and have spawned some babies, I put some Otto's in 2 weeks ago who are also doing fine. I've just added some new Alternanthera Sessilis so if that takes and starts growing nicely then hopefully I've cracked it!.
Probably more of a response than you wanted but it felt good to type it all down for my own sanity! 
Cheers Dave


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## Easternlethal (1 May 2021)

A properly balanced tank should be able to generate its own nutrients, and this process can only happen in the substrate. However it takes a certain topology for this to happen (i.e deep substrate because of the amount of bacteria involved) and organic matter is needed because breaking that down is what creates the nutrients. When that happens, nutrients are released and encourage algae growth if plants are insufficient. When putting osmocote into the soil you are synthesizing this process. 

But since your plants are new or weak they are unable to soak up the nutrients. This is why new tanks with exposed substrates and plants which haven't yet established always get algae and require water changes.

Plants need co2 for respiration which is. short term process and nutrients for growth, which is a longer term process - just like humans with air and food. 

This is why most advice on this forum focuses on taking care of co2 needs. But once your plants are healthy I encourage you to go back to fixing your substrate so that it can feed your plants. A properly established substrate can feed your tank for decades even under high tech conditions.



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## ForestDave (2 May 2021)

Easternlethal said:


> A properly balanced tank should be able to generate its own nutrients, and this process can only happen in the substrate. However it takes a certain topology for this to happen (i.e deep substrate because of the amount of bacteria involved) and organic matter is needed because breaking that down is what creates the nutrients. When that happens, nutrients are released and encourage algae growth if plants are insufficient. When putting osmocote into the soil you are synthesizing this process.
> 
> But since your plants are new or weak they are unable to soak up the nutrients. This is why new tanks with exposed substrates and plants which haven't yet established always get algae and require water changes.
> 
> ...


Thank you for the reply!  
How would you suggest fixing the substrate when the plants are healthy, please? I have a good 3-4" of the aqua soil so plenty to play with. 
Any tips would be much appreciated.


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## Easternlethal (2 May 2021)

The main idea behind an active substrate is to have aerobic activity on top and anaerobic activity lower down.

Achieving this needs proper planning because it takes months for the processes to establish, anaerobic activity can generate hydrogen sulfide which can be dangerous for fish and it can be hard to keep all the nutrients locked within the substrate (if not diatoms and algae can appear on the substrate). 

To solve these issues I usually put a rich thick layer of soil underneath and cover it with sand, which does a good job of trapping all the gasses and nutrients. You can do the same with aquasoil but just make sure the substrate is sufficiently thick - at least 3 inches, and in the early months make sure you keep up with the water changes and fast growing plants to soak up the nutrients (which are actually caused by decomposition of organic matter on the surface of the soil / sand granules and not the processes occurring within the soil that we want).

But you can set all this up and let it establish whilst addressing co2.


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## ForestDave (2 May 2021)

Thanks. 
I expect my snails would like a bit of sand too. What soil do you usually use out of interest?
Cheers 
Dave.


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## Easternlethal (2 May 2021)

Pretty much anything will work. The wider the variety the better: old aquasoil, compost, potting soil, clay, backyard dirt and you can supplement with anything too like osmocote, diatomaceous earth, iron oxide, mgso4..

Here's my latest setup






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## PARAGUAY (2 May 2021)

Thinking the soil is ok These commercial aquatic soils vary anyway from  garden centre Aquatic compost hardly any or no additives to ADA aquasoil very nutrient rich Might be discussed in the " Soil Substrate and Dirt planted tank . Not checked


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## ForestDave (2 May 2021)

Looks good. I’ll give that a go when I rescape. 
I’m not sure if I’d use Osmocote again. I have no idea of what constitutes a good amount or how much is too much.


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## Easternlethal (2 May 2021)

Put as much as you like and measure ammonia nitrites and nitrates regularly in the early months. Then you'll develop a feel for how much your substrate produces

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## ForestDave (2 May 2021)

I’ll maybe experiment with a small livestock free tank. Thanks for the advice. 👍


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