Should have started here and not the pet shop 😬

The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.

NaSho

Aquarium Advice Newbie
Joined
May 7, 2025
Messages
4
Location
Australia
As the title suggests, we went to the petshop came home with a tank and a few days later we added guppies, mollies and tetras. Seemingly all was good until it wasn’t, we were overfeeding and had the light on about 15 hours a day. We lost 2 x bleeding heart Molly’s within a couple of days. Algae started popping up and we took some water into an aquarium shop. We had sky high ammonia as the main issue. Also found out the plants we were recommended weren’t aquarium, they were bog plants so they were trying to head to the surface and the leaves were kind of melting.

We removed ornaments and the bog plants, just leaving a small piece of driftwood and some small dense aquarium plants as we have babies and they need some cover.

We are now several weeks down the track of tank cycling and have lost a couple more Mollys along the way, although they were balloon mollys (I should have read up on those too before buying). At the weekend we still had high nitrites but no ammonia so we did a 50% water change. Currently we have no ammonia, no nitrites and climbing nitrates.

I would just like to know how frequently we should be testing the water now and when we know that the tank has officially cycled.

Thank you for the wealth of knowledge in this group and I will not trust pet store staff again.
 
Until the nitrites reduce to zero on their own ( without water changes) you are not cycled. You are just "diluting the pollution. " This is a picture of the nitrogen cycle in graph form. 1746677895651.jpeg
As you can see, the ammonia goes up then down and the nitrites go up then they go down and the nitrates just go up. You reduce the nitrates with water changes, certain live plants or nitrate absorbing matrix products. So you'll know the tank is cycled when ammonia and nitrites have gone up then down to zero and the nitrates are climbing. If you are several weeks in, I'd be checking your water every two days for a week and if you see rising nitrates with no ammonia or nitrites, you can cut back to testing before adding any new stock ( to confirm the nitrate level is not too high for new fish) or once a week to check your nitrate level so that it does not go higher than 40 PPM. If it goes higher than 40 ppm, that's a sign you need to do a water change to reduce it. (y)

Just to get a better understanding of your situation, please post the actual numbers for your pH, ammonia, nitrite, nitrate, GH ( general hardness) and KH ( carbonate hardness). These numbers will help us better help you. (y)
 
Thanks so much, I’ll put the values in here when we test the water later.
 
Hello. If you never do anything else with a fish tank, do this: If your tank is under 30 gallons you need to remove and replace half the tank water a couple of times a week. A tank 30 gallons or larger will do well with a 50 percent water change weekly. It's been my experience that if you follow this routine, the toxins that can hurt your fish will never reach harmful levels.

B
 
Until the nitrites reduce to zero on their own ( without water changes) you are not cycled. You are just "diluting the pollution. " This is a picture of the nitrogen cycle in graph form. View attachment 391829
As you can see, the ammonia goes up then down and the nitrites go up then they go down and the nitrates just go up. You reduce the nitrates with water changes, certain live plants or nitrate absorbing matrix products. So you'll know the tank is cycled when ammonia and nitrites have gone up then down to zero and the nitrates are climbing. If you are several weeks in, I'd be checking your water every two days for a week and if you see rising nitrates with no ammonia or nitrites, you can cut back to testing before adding any new stock ( to confirm the nitrate level is not too high for new fish) or once a week to check your nitrate level so that it does not go higher than 40 PPM. If it goes higher than 40 ppm, that's a sign you need to do a water change to reduce it. (y)

Just to get a better understanding of your situation, please post the actual numbers for your pH, ammonia, nitrite, nitrate, GH ( general hardness) and KH ( carbonate hardness). These numbers will help us better help you. (y)
We seem to be having a bit of algae growing on the inside of the tank, is this an issue?

Current values; Nitrate 40ppm, Nitrite 0ppm, Hardness 75 (GH)ppm, chlorine 0, alkalinity 80 (KH)ppm, pH 7.2-7.8 (was between the two) and ammonia 0ppm.

We tested ammonia with a kit, other values are from a test strip as we don’t have the full test kit yet.

Thank you 🙂
 
We seem to be having a bit of algae growing on the inside of the tank, is this an issue?

Current values; Nitrate 40ppm, Nitrite 0ppm, Hardness 75 (GH)ppm, chlorine 0, alkalinity 80 (KH)ppm, pH 7.2-7.8 (was between the two) and ammonia 0ppm.

We tested ammonia with a kit, other values are from a test strip as we don’t have the full test kit yet.

Thank you 🙂
Those numbers say " You are cycled!! " :) (y) If your tap water is similar in pH and Hardness to your tank water, you should be lowering your nitrate level with water changes. The closer those values are to each other, the more water you can safely change at a time. You'll want to get the nitrates down to under 20 ppm ( 10 ppm is better) but when there are fish in the tank and the water parameters are too different, it's best to do smaller daily water changes than one large on. 40 PPM is what's considered the upper limit for fish to safely live in. With live plants in the tank, you don't want to eliminate nitrate totally as they feed the plants.
The algae is most likely in response to the higher nitrates. If it's green, it's a combination of too much nutrients and too much light. Cut back on light hours. If it's brown, it's most likely diatoms which are very common in new tanks due to the nitrates. While it is a little unsightly, they will go away on their own in time as long as you keep the nitrate level low. Otherwise, use a siphon hose to get rid of them. (y)
 
Back
Top Bottom