Why is rapid water circulation important?

[John P Coates]

Hi Folks,

I want to understand why rapid water circulation is important in planted tanks. This makes sense for plants whose natural habitat is streams. But, is this always the case?

Intuitively, if the water circulation rate is high (whatever that means in numerical terms), presumably algae spores find it difficult to attach to surfaces - leaves, glass, substrate, wood, etc. I'm only guessing. Can anyone explain?

JPC

 

[Andy Thurston]

To transport nutrients and co2 to the plants and waste products away. 10 x turnover also keeps debris in suspension for longer so it can be removed by the filter

 

[John P Coates]

To transport nutrients and co2 to the plants and waste products away. 10 x turnover also keeps debris in suspension for longer so it can be removed by the filter

Hi, Thanks for the reply. By 'waste products', I presume you mean fish waste products? Could you elaborate on that, please i.e. which waste products? Also, when you say '10x turnover', please explain.

 

[Andy Thurston]

10x filtration turnover, its a minimum guideline amount based on manufacturers quoted flow rates eg. 100l tank is 1000l per hour filter turnover. It doesn't have to be provided by filters, powerheads/wavemakers can be used. Fish waste is one but plants produce waste products too

 

[tim]

Hi John, plants natural environment isn't relevant in an aquarium, most if not all plants in your aquarium will be subject to an extremely different environment than nature, as big clown states most hobbyists stick to the 10x tank volume "rule" to ensure good co2 and nutrient transport to the plants for the extreme lighting levels most hobbyists subject their plants to.

 

[NC10]

I personally think there's a lot of confusion about the flow, especially for noobs. (not that I'm saying you are)

10x plus turnover can be as aggressive or as gentle as you want. The way I've read your first post, about the stream and "rapid", is making me think you believe it's going to be like white water rafting 😀

If 10x were supplied by only one outlet you could well have that effect, but splitting that outlet or using other ways to to supply the 10x will reduce the velocity, more gentle.

If you had a single filter supplying the 10x, a spraybar would be the obvious choice. If you needed more turnover but wanted things to remain calm, you could add a few small powerheads/wavemakers instead of just one for example, or one big power head connected to a spraybar which would also reduce the velocity.

As has already been said, it's all about distributing ferts, Co2 and keeping detritus in suspension. Keeping the excess food and poo in suspension will mean it will be taken up by your filter at some point, instead of it just settling on the substrate and rotting away, potentially leading to problems or more work for yourself 😀

 

[Martin in Holland]

presumably algae spores find it difficult to attach to surfaces

Algae don't care about how rapid the current is, there are many fast flowing rivers filled with algae.

 

[ceg4048]

Hi Folks,

I want to understand why rapid water circulation is important in planted tanks. This makes sense for plants whose natural habitat is streams. But, is this always the case?

Intuitively, if the water circulation rate is high (whatever that means in numerical terms), presumably algae spores find it difficult to attach to surfaces - leaves, glass, substrate, wood, etc. I'm only guessing. Can anyone explain?

Rapid circulation is not the goal. The goal is to have evenly distributed flow across the tank and to have that flow energy high enough to reduce the thickness of the boundary layer at the leaf/water interface. As mentioned by Martin, flow is not really an impediment to the adherence of algal spores to the leaf because they are held like glue within the thin bio-film coating the surfaces.

For a better understanding, review the following threads and the links they contain:
http://www.ukaps.org/forum/threads/flow-rates.32752/#post-348211
http://www.ukaps.org/forum/threads/water-flow-in-the-planted-aquarium.1167/

By 'waste products', I presume you mean fish waste products?

See http://www.ukaps.org/forum/threads/why-have-my-plants-stopped-pearling.11124/#post-118830

Also, when you say '10x turnover', please explain.

The 10X rule refers to a rule of thumb wherein the combined total manufacturer's rating of all pumps and filters used in the tank equal 10 times the tank volume per hour. See http://www.ukaps.org/forum/threads/roma-200-filtration.26000/page-2#post-270036

Cheers,

 

[John P Coates]

Thanks, guys. Lots of useful facts and beautifully reasoned statements. I feel at home here. I really value your feedback. I'm no noob but I have so much to learn!