Deep Gravel - Do You Ever Try To Clean It?

[andyG44]

In my aquarium I have plants and cobbles over the gravel in arrangements, so that disturbing the gravel in order to clean it with a typical gravel cleaner is not really an option. Considering there are about 2.5" of gravel, do you think this is a problem? My opinion is that there will be an equlibrium where bad things will be broken down naturally inside the gravel and the plants will also do their bit as well as the ammonia eating bacteria.

 

[TwoTankAmin]

Never deep vacuum substrate which has live plant roots in it. Am established panted tank has a world of good things going on in such substrate and deep vacuuming will only disrupt this.

 

[Byron]

Your thinking is basically correct.  In a planted aquarium, the substrate is very important, as it is the prime source of CO2 (carbon) and other nutrients.  As organics (fish waste primarily) enter down into the substrate, various bacteria break it down (snails quicken this process) and as it decomposes it releases ammonia/ammonium and CO2, both of which are major macro-nutrients for the plants.
 
Plant roots (of those planted in the substrate obviously) release a considerable amount of oxygen into the substrate, and this aids the aerobic bacteria.  Some areas such as those under large rock or chunks of wood will likely become anaerobic, but this is also necessary and part of a healthy substrate.  De-nitrification is just as important as nitrification in the whole scheme of things.
 
In my 115g tank I never go into the sand at all.  In my 90g I do dig into the open areas of the fine gravel substrate, as I have loaches and they like to burrow, so this has helped I think.  In my 70g I clean over and slightly into the sand along the front; this tank seems prone to algae and cyanobacteria from excess organics, and this has worked to keep these absent.  Each aquarium is different, and once you find the balance you're set.  Provided the tank is not over-stocked or over-fed, both of which will upset this balance, you should be fine.
 
Byron.

 

[TwoTankAmin]

Here is a good piece of research on this topic:
 

 
Nitrification and denitrification in the rhizosphere of the aquatic macrophyte Lobelia dortmanna L.

Nils Risgaard-Petersen’ and Kim Jensen
Institute of Biological Science, Department of Microbial Ecology, University of Aarhus, Ny Munkegade Bldg. 540,
DK-8000 Aarhus C, Denmark
Abstract

Nitrogen and 0, transformations were studied in sediments covered by Lobelia dortmanna L.; a combination of lsN isotope pairing and microsensor (0,, NO,-, and NH,+) techniques were used. Transformation rates and microprofiles were compared with data obtained in bare sediments. The two types of sediment were incubated in doublecompartment chambers connected to a continuous flow-through system. The presence of L. dortmanna profoundly influenced both the nitrification-denitrification activity and porewater profiles of 02, NO,-, and NH,+ within the sediment. The rate of coupled nitrification-denitrification was greater than sixfold higher in L. dortmanna-vegetated sediment than in bare sediment throughout the light-dark cycle. Illumination of the Lobelia sediment reduced denitrification activity by -30%. In contrast, this process was unaffected by light-dark shifts in the bare sediment. Oxygen microprofiles showed that 0, was released from the L. dortmanna roots to the surrounding sediment both during illumination and in darkness. This release of 0, expanded the oxic sediment volume and stimulated nitrification, shown by the high concentrations of NO,- (-30 FM) that accumulated within the rhizosphere. Both lsN, isotope and microsensor data showed that the root-associated nitrification site was surrounded by two sites of denitrification above and below, and this led to a more efficient coupling between nitrification and denitrification in the Lobelia sediment than in the bare sediment.

from http/m.m.aslo.info/lo/toc/vol_42/issue_3/0529.pdf