HOW OFTEN SHOULD A PLANTED TANK BE TORN DOWN ?

If you use substrate ferts, that's fine, adding ferts to the water column will extend the life of them also.

They are not exclusive to the other, they can be used in conjunction if desired, but it's not required.

You still generally need to add K+, Ca, Mg, and Traces to the water column though in CO2 enriched or Excel dosed tanks.

So you just gain a little from that.
Less light, non CO2 makes things grow slower, thus less nutrient demand.

This tank uses EI and has been algae free and running well with a high fish load for 2.5 years:

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Regards,
Tom Barr
 
I would think that the saying "If it aint broke, dont fix it" would apply here. You may never have any problems associated with your substrate. But if you do, that would be the time to worry about it, IMO.
 
crop rotation is a bit differnt from what a planted tank experiances. crop rotation first off helps combat pests that exist in a monculture. then, from a nutriant standpoint, crops require differnt amount sof nutriants. for instance, planting soybeans before maize (aka corn for most americans) allows the nitrogen fixing bacteria in the legumes roots to help create a natrual source on N for the corn the next year. on average, thats enough to reduce the need for commercial N fertilizer by 20%. If you CAN'T artificially fertlize, then by extending fallow seasons, green manure etc will help build up nutriants enough for another crop season. typically, we fertilze a planted aquarium to a very heavy degree, far far higher compartivly to crop ground. The biggest factor in my mind on substrates is probably not that it contains minerals (which will be in a form that isn't readily availble for plant use), but that it has a cation exchange capacity to bind nutriants.

heres a very brief intro to CEC, its a subject that books and lives can be devoted to studying. from http://www.aquabotanic.com/sfintro.htm
Ions Cation exchange capacity
(CEC) Quantifies the ability of media to provide a nutrient reserve for plant uptake. It is the sum of exchangeable cations, or positively charged ions, media can adsorb per unit weight or volume. It is usually measured in milligram equivalents per 100 g or 100 cm3 (meq/100 g or meq/100 cm3, respectively). A high CEC value characterizes media with a high nutrient-holding capacity that can retain nutrients for plant uptake between applications of fertilizer. Media characterized by a high CEC retains nutrients from leaching during irrigation. In addition, a high CEC provides a buffer from abrupt fluctuations in media salinity and pH. Important cations in the cation exchange complex in order of adsorption strength include calcium (Ca2+) > magnesium (Mg2+) > potassium (K+) > ammonium (NH4+), and sodium (Na+). Micronutrients which also are adsorbed to media particles include iron (Fe2+ and Fe3+), manganese (Mn2+), zinc (Zn2+), and copper (Cu2+). The cations bind loosely to negatively charged sites on media particles until they are released into the liquid phase of the media. Once they are released into the media solution, cations are absorbed by plant roots or exchanged for other cations held on the media particles. Anion exchange capacity Some media retains small quantities of anions, negatively charged ions, in addition to cations. However, anion exchange capacities are usually negligible, allowing anions such as nitrate (NO3-), chloride (Cl-), sulphate (SO4-), and phosphate (H2PO4-) to leach from the media.


how much effect it has for an aquarium, i am not sure since we dose for water colum, but for any rooted plant there is going to be some use of the substrate for nutriants.
 
I'd say it's a minor issue (CEC) but can help with leaner dosing routines and lower light tanks with slower growth rates a fair amount.

Substrates can get depleted if they are soil etc with time mainly N, and those might need to be changed out or else water column ferts added etc.

Most things like EC or flourite just needs to be fluffed up once 6-12 months in say 1/4 tank sections each week till the total area is done. By "need" I mean the tank will do better with a deep gravel vacuuming of the Flourite etc every year or so and then replant that section.

The substrate will clog and accumulate too much organic detritus/matter.

Regards,
Tom Barr
 
it is hard sometimes to get plants to grow well even harder if your fish like to eat them, so if you can achieve to grow them faster then they get eaten leave them alone.
 
Thank you to everyone who stated some input that was exactly what i was looking for to help anyone,including myself clear this topic up. Next time i hear someone talk about this i have the knowledge to share with them. Thanks again everyone! BTW nice tank plantbrain!
 
You can also add root tabs if you think your substrate has lost too many nutrients, I have also saw it suggested somewhere to inject some of your liquid ferts directly into your substrate if you have mostly root feeder type plants. I had to do a complete redo when I discovered how big of a mess gravel can make if you overfeed at all and I changed over to sand. As much trouble as that was I wouldn't tear down a tank again unless it was absolutely necessary for the health of my lil fishie buddies :)
 
I would be concerned about any dead roots that are lurking underneath which might be building up sulpher gases.
A few weeks ago I found a banana lily root. The plant had died and snails must have eaten the left over leaves. But the root, it was black and stinky.

Some plants I pull out to trim down and thin out as they grow like weeds. Such as my pink baby tears, camboda, wisteria and javamoss.

With some other plants, if you pull them out to propagate them, trimming the roots can help accelerate the regrowth.
 
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