Plants in or not in "pots"

[Byron]

In another thread, mention was made of growing aquatic plants in pots as opposed to the substrate. Rather than hijack the thread, I thought I'd pose the issue/question in a new thread. There seems to me to be an important negative in using pots, and I'm wondering if others have any information or views on this aspect.

When aquatic plants photosynthesize, they assimilate CO2 via the leaves and oxygen is produced as a by-product. This oxygen is released through the plant's roots. My thinking is that the roots when allowed to spread throughout the substrate will release this oxygen throughout the substrate, helping to keep it healthy. When the roots are confined within a pot, this cannot occur. The oxygen presumably will escape from the pot into the water column (correct or not?) but this is not having any effect on the substrate itself. There would seem to me to be a real benefit to allowing the roots the freedom to oxygenate the substrate, an aspect that takes on even more importance with substrate fish like Corydoras and loaches.

This is quite an impact. When I had my 5-foot and 4-foot tanks planted with Echinodorus species (sword plants), the root system of each one of these plants was incredible. When I pulled the tanks down to move, the root systems extended completely throughout the entire substrate, from side to side. This would have a considerable effect on the health of the substrate.

Comments?

 

[Alice B]

The depth required to anchor crypts is more depth than I want to use, particularly in a sand bed. I had one of those nasty black pockets in a reef tank a long time ago, and my sand got thrown out shortly afterward. I lost a fish in a deep sand bed recently or he jumped out of the tank, suffice to say I haven't seen him in a couple of weeks and that sand bed went down to half an inch. Only my crypts require potting, so I pot them. Other than that I keep Anubias and java fern, neither of which require much burying.

 

[Colin_T]

If you have plants with big root systems (Aponogetons, Cryptocorynes, Echinodorus) and don't have a deep (4-5 inch thick) substrate, then pots/ plastic containers can give the plants more room for root development. You can also put fertilisers in the pots to give the plants more nutrients. If done properly, the fertilisers will not leach into the water and adversely affect water quality.

The amount of oxygen released by plant roots is going to be tiny and will probably be used by bacteria in the substrate. If the substrate is gravel cleaned regularly, or disturbed to loosen it up, then oxygen in the substrate shouldn't be an issue.

Having plants in pots/ containers allows you to move the plants around in their current tank or move them to a different tank and not disturb the root system.

You can use pots to raise plants up in the water column and have wood or rocks in front of the pot. This can allow for various aquascaping designs that doesn't require huge amounts of substrate to be held in position somehow.

 

[TTboy79]

Late reply, so just to give an update about the plants in pots situation since I posted the topic a couple of month ago and I’m happy about this choice. Even if Plants’ roots can’t spread in all the tank being confined, they can find deepness instead and when I put nutrients in each pot I saw the difference!
Plus as you see in the pic I’m even using empty pots as shelters since I’m planning to add dwarf cichlids.

 

[GaryE]

To add a wrinkle - Every dwarf cichlid I've kept and bred (quite a few) has used digging the substrate as part of the courtship and nest building display. It seems extremely important to them, behaviourally.
All ram species are Mikrogeophagus, and all Apistogramma are part of the the eartheater group of Geophagines. Geo=earth, phage=eat. African Pelvicachromis are detritivores and sand sifting is big for them too. Only SA Dicrossus never dug here.
It's a drift from plant pots. But it is part of the discussion of future dwarf cichlids.