Question regarding aquarium soil...

Good question as I would like to know also. Would the answer be different for soil versus other substrate like pool filter sand? Is it based on nutrition being depleted in the soil or something else? I have PFS and didn't think I would ever have to replace the whole thing as long I like the look of it. I have pulled some of it out to bleach it to get rid of algae/BGA. Every 2 or 3 years would be such a hassle!!!

I'd say the answer to the question is relative to the type of soil you have. Some brands like ADA Aquasoil have a finite life. The ammonia enrichment exhausts over time but it continues to transport nutrients well after that. Some soils like Fluorite (basically crushed-up flower pots) will last for many years if not indefinitely. SMS compacts and turns to mud after a couple years. PFS (pool filter sand) lasts as long as you want to keep it.

How long to keep a substrate also depends on the type of plants you grow. Column feeders are much less demanding of nutrient transport via substrate. Root feeders obviously need nutrients delivered to the roots. Root tabs and other types of block ferts can always be added beneath the substrate to extent the duration of a given substrate's life.

Some folks keep a tank planted for a year or two before they reset it. Most of the time that's a personal preference and not an absolute necessity. Most of the folks I know who are into heavy aquascaping and aquatic gardening seldom let a planted setup go for more than a year before they're on to a new look or different plant scheme.

Mark

I use top soil in my tanks and don't change it. Just add fertz like you do in your garden.

I have never changed the gravel in my tank (almost 25 years) since my move. When I first started, I added laterite then just put ordinary gravel over it. I do add root food, but have never changed the gravel.