Journal Is it legit?

[Sarpijk]

Hi all, I came across this guy on youtube who is an advocate of the theory that a thick substrate layer can eliminate the need for water changes. He has even bulid an interior turtle pond that uses a thick substrate and plants. I do not want to do the same but I am curious to know if this is right for critters.

 

[Thumper]

In the german forum there is one guy running his aquarium without waterchanges since 1986. Just changed water once (or twice) due to a leaking tank. You can check it out here.
His main focus is tracking nutrients (NPK, Fe, GH, KH, pH, CO2) weekly, refilling with RO water.

 

[dw1305]

Hi all,
We have a thread which looks at the tanks at "Ocean Aquariums" (video below), where they use this approach. I can't find it, but this was the video that initiated it.



Personally I think that a deep substrate, heavy planting and just topping up with RO allows you "get away" with extremely limited water changes, but all tanks are better with some water changes.

Edit: <This is the discussion on <"PlanetCatfish">.

cheers Darrel

 

[Sarpijk]

I too believe that water changes are essential , the aquarium and the inhabitants seem rejuvenated after a good water change.

How deep is deep when it comes to substrate?

 

[MJQMJQ]

Hi all, I came across this guy on youtube who is an advocate of the theory that a thick substrate layer can eliminate the need for water changes. He has even bulid an interior turtle pond that uses a thick substrate and plants. I do not want to do the same but I am curious to know if this is right for critters.

You need a ridiculous amount of substrate and usually people will use cheaper but less reliable soil eg loam.Also it could release dangerous ammonia if the environment is too anaerobic, hence the need for a substrate that does not contain too much organic material.

https://www.advancedplantedtank.com/tank-substrate-layers.html

 

[Thumper]

Also it could release dangerous ammonia if the environment is too anaerobic

Dont you mean H2S?

 

[MJQMJQ]

Dont you mean H2S?

Oops yes ure right

 

[dw1305]

Hi all,

How deep is deep when it comes to substrate?

That is a "how long is a piece of string" question, there are going to be a lot of variables.

Having said that I think that 6" (15 cm) would be deep even for pea gravel.

Dont you mean H2S?

<"Yes H2S">.

cheers Darrel

 

[Tim Harrison]

Any ideas what the science could be behind the use of deep substrate and minimal or no water changes?

 

[foxfish]

This was my filter set up about 25 years back, 6” of gravel over a supported perforated plate with a 1” gap at the bottom.
A popular marine method of the time and something I was using on my Koi ponds.
In fact I have found by far and away the most successful koi ponds I have built operate a very similar concept but with 2’ of gavel and heavily planted in the gravel bed.
Some of these pond are 35 years old and still running without ever having a major water change.

 

[Parablennius]

Deep substrate becomes anoxic, nitrate is converted by denitrifying bacteria into N2 which escapes as gas. Deep sand beds have been used in marine aquaria to remove nitrate, even extreme ones like RDSB, Remote deep sand beds where a large vessel was filled almost to the top with oolitic sand and filtered aquarium water was passed across it and returned to the aquarium. Anthony Calfo was a big proponent of these. I think the example he used was something akin to a waste bin. The exchange rate to the bottom of the bin would be very slow but it would happen. Not sure about the water change aspect though.

 

[dw1305]

Hi all,

Any ideas what the science could be behind the use of deep substrate and minimal or no water changes?

There are quite a few references from recirculating aquaculture systems (RAS) and from waste water treatment looking at combined aerobic/anaerobic processes. Probably the ones that are of the most interest to us are the studies that have tried to quantify the contribution of both processes in <"vertical flow constructed wetlands">.

The PlanetCatfish thread <"Using deep gravel and bacteria to control nitrogen"> has a few references. Most of the "meat" is in the last 3 pages. I've posted quite a lot on the PC thread, so it references UKAPS, and dips in and out of our threads.

In fact I have found by far and away the most successful koi ponds I have built operate a very similar concept but with 2’ of gavel and heavily planted in the gravel bed. Some of these pond are 35 years old and still running without ever having a major water change.

I really <"like these kinds of filters">, and I could see why they would stay in full working order over time. This is actually a type of the "vertical flow constructed wetland" mentioned above.

cheers Darrel

 

[Tim Harrison]

Thanks @foxfish and @Parablennius, I used something like that with coral sand in reverse flow - UGF plates attached to a canister filter for my Heath Robinson reef tank, back in the day before all the complicated equipment seemed to become essential. It worked really well. I think all in, I had change from a couple of hundred quid after setting up a 50 gallon tank. Now a conventional marine tank would cost well over a grand.

Similarly with a normal UGF in a freshwater planted tank, soil sandwiched between pea gravel, again it worked very well, little or no water changes required.

And thanks Darrel, @dw1305, for the links, very interesting reading. I was more thinking about how a deep soil substrate would work and if I was missing anything. I guess the principle is similar to the above but plants play a large role.

 

[Parablennius]

One of the key elements in a RDSB, as distinct from an "in tank" one is that the water is filtered and mechanically clean so that the RDSB remains free from any sediments. Also that the bulk of the flow is across the sand rather than directly through it, which takes place at a very much reduced rate.

 

[Witcher]

Hi all, I came across this guy on youtube who is an advocate of the theory that a thick substrate layer can eliminate the need for water changes.

What I can see there is a nice eleocharis-like carpet covered with algae - so I think water changes are needed to avoid cumulation of anything what makes the algae thriving.

 

[dw1305]

Hi all,

I was more thinking about how a deep soil substrate would work and if I was missing anything. I guess the principle is similar to the above but plants play a large role.

The finer grained substrates will slow oxygen diffusion, so you are likely to have denitrification nearer the surface and potentially sulphate reducing conditions lower in the substrate, it is more analogous to a <"Winogradsky column"> than a coarser grained substrate would be.

There are plants that can transport oxygen deep into anaerobic substrates, like Rhizopora, <"Typha and Nelumbo"> etc. The search term we are interested in is <"Radial Oxygen Loss">. This is a <"Nelumbo rhizome">, showing the oxygen transport system.

cheers Darrel

 

[mort]

One important aspect of marine deep sand beds is the microfauna that inhabit them. These micro worms, starfish and other critters burrow through the substrate allowing water to slowly percolate through the layers but at a speed that doesn't impact the different oxygenated zones. Without these critters the bed will stagnate. I'd imagine plant root growth will have a similar influence in a freshwater setup unless you are using a plenum.
With marines a 4" bed is normally the shallowest depth suggested to promote dentrification but this only really works if you get a fine enough substrate to allow for oxygen reduction. It's ideally better to have a deeper layer or a mix of fine substrates to reduce the pore spaces and allow for a slow percolation of water. My guess would be that going to deep in a freshwater system would increase the likelihood of problems at worst, or have no real extra benefit at best.

 

[Tim Harrison]

I know that macrophytes can change the physicochemical environment of sediments through ROL etc which in turn will influence microbial communities and the removal of N.
But what particular advantage does a deep soil substrate infer on water quality beyond the part of the rhizosphere that interfaces with the water column?
I'm guessing there isn't much in the way of water movement beyond the first few cms or so particularly in a sediment composed of fine particles.

 

[dw1305]

Hi all,

But what particular advantage does a deep soil substrate infer on water quality beyond the part of the rhizosphere that interfaces with the water column?

You would just get a reduction in nitrate in the water column, personally I'd much rather have a floating plant and water changes.

Marine aquarists are much more limited in terms of <"vascular plants"> (and there aren't floating ones), and they may also want to reduce the volume of water changed due to the cost of marine salt etc.

The same applies to commercial aquaculture, producers are often keen to use re-circulating systems to limit there use of water and reduce costs of effluent disposal etc.

cheers Darrel

 

[Onoma1]

Really fascinating discussio .

One of my first (naive) posts to the forum I brought up the issue of mycrrhizal fungi.

I still wonder if, deep substrates in conjunction with roots of the plant's Darrel identified may allow more micro fauna. The evidence on mycrrhizal fungi seems to be that their presence leads to more resilience and better growth in plants. Would this then allow more effective proocessing and better elasticity in coping with changes?

https://www.ukaps.org/forum/threads...he-aquascape-mycorrhizal-fungi-and-art.55427/