Newbie

[Sir Guppy]

Well planted tank still need water changes to remove all the things excreted by the fish and to replenish things both fish and plants take from the water.

@Samandy Could you post a photo of the eggs please - assuming they've been laid somewhere easy to photograph. Cories usually deposit eggs on the tank walls, plants, decor etc.

If a tank is well enough planted, the plants will clean the tank.
Plants need certain nutrients yes, but those can be supplied through top offs and in some cases crushed coral.

When you said things both fish and plants take from the water-what things do fish take??
All they need is oxygen, which is supplied by surface agitation.

 

[Sir Guppy]

You need to do water changes regularly even if the water tests are good. There are lots of things in water that we can't test for and they need to be removed as well.

You do water changes for a number of reasons.
1) to reduce nutrients like ammonia, nitrite & nitrate.
2) to dilute disease organisms in the water.
3) to keep the pH, KH and GH stable.
4) to dilute nitric acid produced by fish food and waste breaking down.
5) to dilute stress chemicals (pheromones/ allomones) released by the fish.
6) to dilute un-used plant fertiliser so you don't overdose the fish when you add more.
7) to remove fish waste and other rotting organic matter.

Fish live in a soup of microscopic organisms including bacteria, fungus, viruses, protozoans, worms, flukes and various other things that make your skin crawl. Doing a big water change and gravel cleaning the substrate on a regular basis will dilute these organisms and reduce their numbers in the water, thus making it a safer and healthier environment for the fish.

If you do a 25% water change each week you leave behind 75% of the bad stuff in the water.
If you do a 50% water change each week you leave behind 50% of the bad stuff in the water.
If you do a 75% water change each week you leave behind 25% of the bad stuff in the water.
If you don't do any water changes, you leave all the nasty stuff in the aquarium with the fish.

Imagine living in your house with no windows, doors, toilet, bathroom or anything. You eat and poop in the environment and have no clean air. Eventually you end up living in your own filth, which would probably be made worse by you throwing up due to the smell. You would get sick very quickly and probably die unless someone came to clean up regularly and open the place up to let in fresh air.

Fish live in their own waste. Their tank and filter is full of fish poop. The water they breath is filtered through fish poop. Cleaning filters, gravel and doing big regular water changes, removes a lot of this poop and harmful micro-organisms, and makes the environment cleaner and healthier for the fish.

Whilst you might not have ammonia, nitrite or nitrate problems, the number of micro-organisms in your tank will be growing exponentially due to lack of water changes and this will eventually cause problems to the fish. Water changes should be done to dilute disease organisms, if for no other reason.

My shrimp and snails take care of the poop. The plants clean the tank.

You said: “ the number of micro-organisms in your tank will be growing exponentially due to lack of water changes and this will eventually cause problems to the fish.”
I never heard of this! Where did you learn this?

 

[MaloK]

Aquaria can lean from the nearly completely nutrients deprived, with a clogged sponge filter environment where everything survives, looks alright, but...

To an enriched environment where everything thrives and will create a lot more waste and requires more filter rinses more maintenance, more clean water, more flow.

It's you that decides where the balance points.

 

[Colin_T]

My shrimp and snails take care of the poop. The plants clean the tank.

You said: “ the number of micro-organisms in your tank will be growing exponentially due to lack of water changes and this will eventually cause problems to the fish.”
I never heard of this! Where did you learn this?

Talking to scientists and reading research papers. We had a number of scientists in ANGFA and various other fish clubs, and some of them used to spend a lot of time looking at the things in aquarium, pond and river water. Aquariums are closed systems with a limited amount of water and the protozoa, viruses, bacteria and fungus (among other things) grow in the water. They are continuously growing all the time. They grow faster in warm water (tropical aquariums) and slower in cold water aquariums, but they still grow and reproduce and their numbers build up. In a river, most of these microscopic organisms get washed away from the fish but in the confines of a pond or aquarium, there is nothing to wash them away except water changes.

 

[Sir Guppy]

Interesting ..still gonna stick with no water changes however. I have had no problems so far, and have heard of people going as far as over 3 years successfully without a single water change.
If problems ever do show up I will if necessary, but until then I will not at all.