Advice on levels

[debswhite]

HI all

I have recently got a 100 litre tank. As is the normal advice here in the UK, I set the tank up, put in the gravel, ornaments and plants along with water conditioner and biological enhancer and left to run for a week. Water sample was tested at shop and they said I was good to go with fish. I started with a few and completed a water change. Levels seemed ok and then the angel fish started gasping for air and died within a few hours. Other fish are perfectly fine.

Tested water at home and ammonia was relatively high. Have since done a 30% water change 3 days on the trot adding biological enhancer and water conditioner each time. Water looks great, fish very happy and active, reduced feeding and ammonia pretty much 0.

Issue is now the Nitrite level is at around 5ppm and Nitrate level 80ppm. 20% water change was done 4 hours beforehand.

Might be a silly assumption but is that because of the quick reduction (72 hours) in ammonia? Is it going through the cycle and as a high level of nitrate is present, the nitrite will lower naturally? Do I need to intervene?

 

[Aiken Drum]

You are in the process of cycling your tank. The first stage is that microbes that consume ammonia and turn it into nitrite start to establish. This is where you are at. Once nitrite shows up your nitrite to nitrate microbes can start to establish.

Your cycle is establishing. Your ammonia is at zero through a combination of those microbes and your water changes. Your nitrite is at a dangerously high level and will be causing long term organ damage. You might not be seeing it, but its happening and could cause health issues down the line.

You need to get that nitrite to no higher than 0.5ppm. Based on 5ppm that needs 3 or 4 back to back 50% water changes. Do them an hour or so apart, and do them as soon as you are able.

Going forward, test your water daily for ammonia and nitrite. Add them together. If they total higher than 0.5ppm then change enough water to get it below that 0.5ppm target. Until you get your water quality under control, light feeding. Every day as much as is eaten in 1 minute, or every 2 days as much as is eaten in 2 to 3 minutes. Dont add any more fish until your cycled sufficiently for the fish you have.

 

[Andy Sager]

The short answer is Yes, your tank is cycling and you need to intervene. The long answer is.....
When cycling a tank, you are creating or adding the microbes that convert ammonia into nitrites ( let's call them Microbe A) and nitrites into nitrates(Let's call these Microbe B). These are living organisms so when you added the " biological enhancer", which should be microbes A & B, and then did nothing for a week, you starved the microbes you added and they died so when the shop tested your water, of course it would be good because you had nothing in the tank to make it not good. See, the beginning of a cycle and the end of the cycle look identical except that at the end, you should have a nitrate reading. The problem is, some water sources already have a nitrate level so you need to know if your nitrates are coming from the microbes or the water source. That means you have to test your source water to confirm they are not coming from there before adding it to the tank.
The nitrite would naturally come down to 0 over some time because of the Microbe B preset but since you have fish in the tank and nitrites are toxic to the fish, you need to do water changes to keep them low so that your microbes catch up to the level faster. You'll want to do 50% water changes every day to other day ( depending on the nitrite level) to keep the nitrite level below 1 PPM. Nitrites over 5PPM are toxic to the fish. Between 1 and 5 are stressful but not as deadly as over 5 PPM. You also want to keep your nitrate level under 40 PPM so the first 50% water change should help reduce your 80 PPM to 40 ppm and the next water change will bring them lower and so on. Unless you have live plants in the tank, a 0 nitrate level is ideal ( but not always easy to achieve. )

Lastly, keep in mind that the microbes A & B ( also known as the biological filter bed) is a living breathing thing that grows and shrinks based on the amount of ammonia present in the tank. Fish produce ammonia from breathing and eating ( actually what happens AFTER they ate ) so for example, if you have 10 small fish when your tank finishes cycling, you only have enough microbes to handle the amount of ammonia produced by those 10 small fish. When you add more fish, your biological bed needs to grow so you will be doing " mini cycles" while this happens. The good news is that these cycles, if you don't add too many fish at once, will finish in just hours, not days. If you cycle a tank with 5 large fish, when it finishes, there are enough microbes to handle the ammonia produced by the 5 large fish. If you were to remove the 5 large fish and replace them with 10 small fish, those 10 small fish will probably not produce as much ammonia as the 5 large fish so there will be some die off of the microbes but only until they balance out for the amount of ammonia being produced. Keeping all this in mind, say you cycled the tank with the 5 large fish but you remove 3 of them for whatever reason so that there are only 2 large fish in the tank, 2 months later you can't add 3 large fish again and not expect the tank to have issues. The most common problem is when people remember what they had in the tank before..... months before, and forget that the biological bed shrunk in the time since they had all those fish in the tank so they are cycling their tanks again. It will happen faster since there is an active biological bed already present but it probably won't be an overnight thing.

I told you this was the long answer but hopefully you understand why what is happening is happening. Time to do water changes.

 

[debswhite]

Thank you both - so so helpful. I had done a 20% water change 8 hours ago and I have just done another 50% water change. I will test again in a couple of hours and then repeat tomorrow.

Your advice has helped expand why I'm at where I'm at in the cycle and I'm confident I can solve it then wait a while before even thinking about anymore fish (if at all!!).

Fingers crossed!

 

[Andy Sager]

Thank you both - so so helpful. I had done a 20% water change 8 hours ago and I have just done another 50% water change. I will test again in a couple of hours and then repeat tomorrow.

Your advice has helped expand why I'm at where I'm at in the cycle and I'm confident I can solve it then wait a while before even thinking about anymore fish (if at all!!).

Fingers crossed!

The good news is you are doing what they call a " Fish in" cycle. This was the only way it was done for decades so it's very doable. You just need to keep the levels under the toxic zone with water changes and when/if you add more fish, you add them slowly and not too many too often.