# Inert or not inert?



## nothreat33 (Aug 5, 2019)

I bought fluval startup for my new 5g. Seemed like a very popular choice on another planted tank forum. I didnt give it much thought. What is the most popular substrate used on this forum? And wouldn't you want substrate with nutrients for root plants? Wouldn't excellent circulation be required for liquid dosing to penetrate the inert substrate?

I'm not sure which type to pick.


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## Asteroid (Jul 26, 2018)

Long story short, all the aquatic plants we grow can take in nutrients through the leaves, so technically you don't need any nutrients in the substrate as long as your dosing the water column.

There are highly successful tanks using inert and active substrates. It really depends on preference and the goals you have for the tank. Some substrates buffer the water for certain livestock etc.


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## minorhero (Mar 28, 2019)

I am not sure if there is a clear most popular substrate here. If you want an inert substrate that is black the clear favorite is probably black diamond blasting sand you buy from tractor supply. If you want an inert sand substrate in a more natural color its a mix of caribsea super naturals or pool filter sand. If you want substrates with high cec value its either safe-t-sorb, or turface as most popular. If you want active substrates there is a pretty good mix with dirt being right up there with all the major brands of aquasoils. Eco-complete is there as an honorary mention, but there is such a polarizing view on that one I don't know if I could label it as most popular.


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## Blue Ridge Reef (Feb 10, 2008)

It's important to understand that most aqua soils lower KH and pH in the aquarium and that is not what everyone is after. Great for Caridina shrimp and many plants, but not something I'd want to use in say, a livebearer tank. It also has a finite lifespan. I use it myself in some situations but would opt for something inert if setting up a typical planted fish aquarium.

I like Eco Complete. I like Flourite. I like plain ol' Estes gravel. I have experienced more drawbacks with sand than many here. I have had much worse experiences with potting soil underneath a substrate than many here. The next poster may come along with opposite feeling on substrates and neither of us would be wrong. There are lots of factors to a healthy planted aquarium. Substrate is a part of it but if all else is right, plants will grow in most any of them.


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## varanidguy (Sep 8, 2017)

You can do a happy compromise and use organic soil capped with #20 pool filter sand. It won't buffer your water but you'll get a very rich substrate, plus the #20 pool filter sand isn't so fine that nutrients in the water column won't penetrate.


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## nothreat33 (Aug 5, 2019)

> It also has a finite lifespan


what happens when that life span is up? Do I have to redo the tank? Or are the nutrients simply gone? Are there other drawbacks or bad things that happen when its life span is up?


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## Blue Ridge Reef (Feb 10, 2008)

That is a bridge I've yet to cross, but I've seen some odd photos on threads here. One guy's turned to mud almost, but I had to wonder if something else wasn't going on to create that. My oldest tank using it is about 2 years at this point and I see no evidence that it has changed. I do use remineralized RO/DI water exclusively on these Caridina tanks though. It would seem logical that that would happen more quickly the harder the source water used. I think @somewhatshocked has been using them for a decade or so, hopefully he or someone else who has experienced what happens when they are exhausted will chime in.


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## Diana Walstad (Aug 17, 2019)

nothreat33 said:


> what happens when that life span is up? Do I have to redo the tank? Or are the nutrients simply gone? Are there other drawbacks or bad things that happen when its life span is up?


Fishfood, which contains all nutrients that plants need, keeps the soil fertile. The fish are one means of converting fishfood into plant nutrients. Snails, bacteria and fungi also provide assistance in this recycling process. Of course, if you continuously clean the tank and change water, then you interfere with this natural replenishment.


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## varanidguy (Sep 8, 2017)

Diana Walstad said:


> Fishfood, which contains all nutrients that plants need, keeps the soil fertile. The fish are one means of converting fishfood into plant nutrients. Snails, bacteria and fungi also provide assistance in this recycling process. Of course, if you continuously clean the tank and change water, then you interfere with this natural replenishment.


I'm curious, what nutrients does fish food contain, specifically? I am aware that it can provide nitrogen and phosphorus...in the grand scheme. But I wasn't aware that it's a complete and balanced fertilizer.


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## ursamajor (Oct 6, 2015)

Diana Walstad said:


> Fishfood, which contains all nutrients that plants need, keeps the soil fertile. The fish are one means of converting fishfood into plant nutrients. Snails, bacteria and fungi also provide assistance in this recycling process. Of course, if you continuously clean the tank and change water, then you interfere with this natural replenishment.


I don't think this is quite true. Fish food and waste are not comprehensive sources of nutrients. They can be good sources of nitrogen and phosphorus, but tanks relying primarily on fish waste are usually deficient in potassium and certain micros. To quote Dennis Wong, no fish I know of produces chelated iron as waste.


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## germanblueramlover (Jun 9, 2013)

It has trace elements too - I believe most fish foods contain copper, off the top of my head. But I do think most people end up needing to use some form of fertilizer to maintain growth in the end.

My tank has been woefully unfertilized for years, and the plants are growing - or at least holding steady, depending on species. But since I've been being more diligent with root tabs, column dosing etc, there's been a very dramatic improvement in their size and appearance.


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## Asteroid (Jul 26, 2018)

Diana Walstad said:


> Fishfood, which contains all nutrients that plants need, keeps the soil fertile. The fish are one means of converting fishfood into plant nutrients. Snails, bacteria and fungi also provide assistance in this recycling process. Of course, if you continuously clean the tank and change water, then you interfere with this natural replenishment.


Well this might work for a low-energized limited system. Limited in terms of light and co2 enrichment. If we are talking about bringing in more nutrients to depleted AQUA soil then you can add another layer and/or dose the water column.


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## DaveKS (Apr 2, 2019)

varanidguy said:


> I'm curious, what nutrients does fish food contain, specifically? I am aware that it can provide nitrogen and phosphorus...in the grand scheme. But I wasn't aware that it's a complete and balanced fertilizer.


Fish food contains most every element that was used by the plant or animal it’s based upon to build its cells. Some may not be in there in concentration we need but pretty much everything is there.


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## KayakJimW (Aug 12, 2016)

When I hear active substrates lifespan being used up, I think more in terms of losing buffering capacity. For those keeping fancier caridina shrimp or targeting a 0KH



Diana Walstad said:


> Fishfood, which contains all nutrients that plants need, keeps the soil fertile. The fish are one means of converting fishfood into plant nutrients. Snails, bacteria and fungi also provide assistance in this recycling process. Of course, if you continuously clean the tank and change water, then you interfere with this natural replenishment.


The Diana Walstad!? So glad to see you here. You've definitely made a name for yourself in the aquarium world and I look forward to your posts on this forum. Welcome!


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## varanidguy (Sep 8, 2017)

DaveKS said:


> Fish food contains most every element that was used by the plant or animal it’s based upon to build its cells. Some may not be in there in concentration we need but pretty much everything is there.




Interesting. I’m genuinely not trying to be rude or obtuse with the question. It’s just that we are accustomed to dosing a wide range and specific types of plant specific nutrients, I wasn’t aware that fish food could fill this role.


Sent from my iPhone using Tapatalk


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## nothreat33 (Aug 5, 2019)

That can't be the real diana walstad can it?


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## somewhatshocked (Aug 8, 2011)

It's the real Diana Walstad.


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## Desert Pupfish (May 6, 2019)

varanidguy said:


> Interesting. I’m genuinely not trying to be rude or obtuse with the question. It’s just that we are accustomed to dosing a wide range and specific types of plant specific nutrients, I wasn’t aware that fish food could fill this role.
> Sent from my iPhone using Tapatalk


The Walstad Method specifically refers to low light tanks with a active dirt substrate that supplies much of what's needed for the slow growing plants that she recommends after the initial ammonia release--supplemented of course by the converted fish food. For the high light, CO2 injected tanks with lots of fast growing stem plants most people have on here, you're right that you'd need to dose high amounts and a wide range of nutrients to make it work. And of course the frequent water changes mean the nutrients get dumped and you have to keep re-dosing. 

It's two entirely different approaches, really. Those of us trying to do low tech find ourselves in the middle--trying to incorporate the elements of each that will make our unholy hybrids work.....


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## varanidguy (Sep 8, 2017)

Desert Pupfish said:


> The Walstad Method specifically refers to low light tanks with a active dirt substrate that supplies much of what's needed for the slow growing plants that she recommends after the initial ammonia release--supplemented of course by the converted fish food. For the high light, CO2 injected tanks with lots of fast growing stem plants most people have on here, you're right that you'd need to dose high amounts and a wide range of nutrients to make it work. And of course the frequent water changes mean the nutrients get dumped and you have to keep re-dosing.
> 
> It's two entirely different approaches, really. Those of us trying to do low tech find ourselves in the middle--trying to incorporate the elements of each that will make our unholy hybrids work.....


LOL @ unholy hybrids

Makes sense then, so in the Walstad tank, we're relying on fish waste and uneaten food to basically compost and enrich the soil, keeping the nutrient levels up for the plants. Essentially what we do in our veggie gardens.


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## Asteroid (Jul 26, 2018)

varanidguy said:


> LOL @ unholy hybrids
> 
> Makes sense then, so in the Walstad tank, we're relying on fish waste and uneaten food to basically compost and enrich the soil, keeping the nutrient levels up for the plants. Essentially what we do in our veggie gardens.


Yes, it's really at the opposite end of the spectrum when your comparing to a hi-tech tank where you want to remove as much organic waste as possible. This will allow you to use more light, more plant selection and the system isn't really limited in anyway. One is all about growing plants in a more "natural way" and the other is tilted more toward aesthetics.


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