Water change thread. Another one?

I am reasonable new to fish keeping. I have not done a water change on my little 25 litre tank since adding fish to it about 6 months ago. I test the water regularly and it seems fine. The only small issue I have had is some brown algae growing on hard surfaces. It has not grown back since cleaning but some spots that I didn't get to are still there.

I only do top ups with RO water from evaporation. I avoid using our tap water, it has carbonate levels 300 - 400ppm, PH close to 8 and nitrate levels around 25 - 50 ppm. The chlorine levels in the tap water are near 0 though.

The tank is planted and has a large growth of moss. It is gravel over a soil substrate, can't remember what type of aquarium soil. The soil looks light brown, maybe clay based. There are 4 fish, a Guppy, Sparkling Gourami and 2 Khuli Loaches. I guess it is a light bio load despite the small tank size. The filtration is simple with a stick-on submersible rated for a 50L tank with an overhead fountain type output. It makes a nice water feature type sound and adds lots of oxygen bubbles.

Reading through these forums most keepers seem to recommend at least a weekly 20% change. I was concerned I had never done one since adding the fish months ago. I have done a 20% water change today and sucked a little at the gravel. The water that came out looked clean.

Do I need to do weekly water changes on this tank?

How many sparkling gouramis are there and are the "4 fish" the fish you listed or are there 4 more fish? Khuli loaches need at least 8 and a much bigger tank, and guppies like to have a couple friends.

A picture of the tank would be helpful.

What are the exact water parameters? And what are you using to test your water?

Depending on how many plants there are you should start off by doing 10-20% water changes, then I think 30% water change every week should be good. Unfortunately though the Khuli loaches are not happy and I'd recommend giving them away to a LFS or some who has a bigger tank with more Khulis.

Back when I had fish 20 years ago, I wasn’t doing water changes, only refilling for evaporation… I obviously didn’t have any challenging to keep fish, at least that lasted… but I will admit, when I moved to a new place that had a ton of widows, and I added a bunch of house plants, I started filling gallon milk jugs to water the plants, vacuuming the gravel while I filed jugs, from the aquariums… we had a lot of plants, so I had 12-16 gallon jugs I kept in milk crates… for watering the plants, and I only did the water changes as often as the plants emptied the jugs… the tanks and the house plants both responded positively… we literally had a jungle in the room with all the windows, and my fish grew faster, and got more colorful…

So depending on your situation, you may get by with very limited water changes, but the benefits are great for doing them

My article on water changes pinned at the head of the Tropical Discussion forum should answer your questions.


You cannot use water tests to determine when water changes are needed, except obviously when something is clearly wrong. Regular partial water changes maintain stability.

BettaFishGirl said:

How many sparkling gouramis are there and are the "4 fish" the fish you listed or are there 4 more fish? Khuli loaches need at least 8 and a much bigger tank, and guppies like to have a couple friends.

A picture of the tank would be helpful.

What are the exact water parameters? And what are you using to test your water?

Depending on how many plants there are you should start off by doing 10-20% water changes, then I think 30% water change every week should be good. Unfortunately though the Khuli loaches are not happy and I'd recommend giving them away to a LFS or some who has a bigger tank with more Khulis.

Click to expand...

Hi,

Only 1 Gourami and 1 Guppy. There were 2 Gourami's, they didn't get along. Having since read more on fish behaviour it was probably due to the small space and low numbers. I then added two male fancy Guppies and the same thing happened with them, unfortunately. Now it is just the 1 Guppy and 1 Gourami. At least they seem to leave each other alone. The 2 Khuli's are my favourite. They can often be seen out and about.

Got some API testers and some cheaper strips.
PH is 76 - 7.7 (despite using RO which reads about 6.6 out of the container it is always stable in the tank. I was trying to reduce it but gave up thinking as long as it is stable.)
Ammonia - 0
Nitrite - 0
Nitrate - 20 ppm
Carbonates - 40 ppm
Total Hardness - 100 ppm (get some conflicting results on this, maybe need a better test)

I was always going to upgrade to a larger tank if this one was successful. After reading your post I think I need to make that a bit more urgent. I want to keep Khuli's, I like them.

Picture below. Looks like a bit of algae in the gravel against the glass. Not sure what the different colours are in the soil substrate. The blue is the original gravel before I restarted the tank. My daughter wanted to leave some of it in there. I think I might use sand if I start a new tank.

Thanks for responding.

Byron said:

My article on water changes pinned at the head of the Tropical Discussion forum should answer your questions.

Regular Partial Water Changes

Byron Hosking November, 2010 (rev April 2021) Nothing is more important when it comes to aquarium maintenance than regular partial water changes. The adage “an ounce of prevention is worth a pound of cure” certainly applies here. One frequently reads of products that will reduce the need for...

www.fishforums.net

You cannot use water tests to determine when water changes are needed, except obviously when something is clearly wrong. Regular partial water changes maintain stability.

Click to expand...

Yeah, that is what I have been reading from this forum. I was mistaken in thinking if the tests were ok then leave it. I will start it as a routine. Using RO I am thinking I would need to add minerals back, or will I get enough from the stuff already in there?

Jetto said:

Yeah, that is what I have been reading from this forum. I was mistaken in thinking if the tests were ok then leave it. I will start it as a routine. Using RO I am thinking I would need to add minerals back, or will I get enough from the stuff already in there?

Click to expand...

Depends uponthe fish species. You give the GH as 100 (I assume this is 100ppm rather than 100 dH) so this is soft water. Is this the RO? Or tap water? Or a mix?

And, what fish are in the tank?

Byron said:

Depends uponthe fish species. You give the GH as 100 (I assume this is 100ppm rather than 100 dH) so this is soft water. Is this the RO? Or tap water? Or a mix?

And, what fish are in the tank?

Click to expand...

It started off as tap water, have been using RO ever since (6 months). Was recomeneded due to our tap water parameters being so bad.

What fish species?

Byron said:

What fish species?

Click to expand...

odd mix, 1 Guppy, 1 Sparkling Gourami and 2 Khuli loaches.

Jetto said:

odd mix, 1 Guppy, 1 Sparkling Gourami and 2 Khuli loaches.

Click to expand...

Guppy being a livebearer is moderately hard, but these days I wouldn't worry, but don't get more of any livebearers. The other fish are soft water, so they do not need any remineralization. Going forward, only consider soft water fish, which pretty much covers South American and SE Asian species, with a few exceptions. I had all these with my zero GH/KH water.

The Khulis are not happy at all, and scared because there are only 2. Definitely get a bigger tank and get more Khulis and sparkling gouramis, because the gourami is scared too.

Here's my take - for the first 100 years of the hobby, no one did water changes. There was no idea they could help, and no understanding of the dynamics of an aquarium. But fish stayed alive, and the tougher ones did well.

Then came the water change era, and having kept fish in both (old guy here) I am glad it did. My fish live way longer, have better colour, are more active and breed more. I used to think a cardinal tetra living 3 years was big. Now they live 7-9 years here, and that's bigger.

So the choice is yours. Your fish can live with no water changes and RO top ups. It is possible.

if you decide to go with water changes, do a lot of small ones to start. Your water is going to be, umm, special, and your fish will have adapted to it. A sudden change to clean water could kill them, as they need time for the regular systems to kick in.