Ph dropping in goldfish tank

[Roz]

BACKGROUND
I have a 50L tank with 4 baby fantail goldfish (originally 3 but now Goldie lives with us because he wasn't doing too well in his first home). All fish seem well and two have grown rapidly! The other two not so well - Goldie has only just joined the gang but Lightening McQueen has a little trouble eating - his mouth isn't as big as the others and so I try and direct the smallest morsels to him.

Am feeding soaked flakes twice a day (have tried sinking pellets but they have trouble finding them), and pea snacks once or twice a day.

I have a HoB filter and bubbles, and test the water and do a 20% PWC every second day until I can afford a bigger tank in a month.

The tank has been running now for several weeks.

The tank has always had real plants, but I have to replace most every second week - perhaps not doing well due to lack of light?

THE ISSUE
Over those weeks I have noticed the ph continually dropping - from about 7.6 to 6.4.

Ammonia and nitrite always 0 and nitrate 40 or below.

Can't seem to work out what is happening.

I have tried researching the issue on the internet, but I trust the advice on this forum more.

I am a complete beginner, so any advice will be of great help to me

 

[Roz]

Sorry - Ammonia almost always 0, but I have trouble reading the colour chart. Nitrite definitely always 0.

 

[jlk]

The amount of ammonia this many messy fish are producing in a very small tank are forcing your good bacteria to work in overdrive. They need KH to process ammonia. As they use up KH, your ph becomes unstable and crashes. Your water change schedule is far from sufficient to keep your KH stable. Increasing your water changes to 50+% at least every other day to daily to help keep KH levels more stable until you can get these guys in much larger tank. An unstable ph that is crashing this drastically will result in health problems for these guys and the weakest fish will be affected first (as you are seeing). Please ask if you have questions!

 

[Roz]

Thank you - I'll increase water changes to 50%. I'll get back to you with any questions.

The fishies are all very active.

I'll buy my new tank next week, and think I'll move the fishies in straight away and do a fish-in cycle. I know that is not ideal but think it might be best. What do you suggest?

 

[jlk]

I agree with doing that. Just make sure you move your present filter to the new tank along with the new filter. This will carry over your established bacteria. Then it will simply be a matter of testing daily for spikes in toxins and doing water changes as needed to keep them under control (less than .25ppm). If you find you are still having ph issues in the new tank then you may need to add a natural buffer such as aragonite or crushed coral to your filter (in a mesh bag/piece of pantyhose). Cross that bridge if it becomes an issue again!

 

[Roz]

Ok, am a bit scared about doing that it, but will follow the instructions in the link you gave me in a previous thread.

I noticed this morning that Lightening McQueen (the fishie with the smaller mouth) has a torn rear fin. From the advice I have read to date, I imagine that very clean water will be essential for the fin to heal

 

[jlk]

Yep, lots and lots of healthy, stable water. Just keep an eye on the fin for any signs of infection. Now, are you scared of a fish-in cycle or adding a buffer? No reason to be scared of either!

 

[Roz]

Sorry, message sent before finishing - if you don't mind I might post a new thread under unhealthy fish if he needs help. At the moment he is behaving normally - enthusiastic about food and having fun exploring the plant leaves and little tunnel, which are his favourite things to do.

 

[Roz]

Hello, just worried about the fish-in cycle, but will make sure I have the instructions with me and know that the advice on this forum is fantastic - far superior to any of my books or the lfs.

Thank you!

 

[jlk]

It will be a breeze for you as long as you move the current filter (and media) to the new tank and run it with the new filter. This will help seed your new tank and filter and hopefully you will not see any spikes in toxins. If you do, it simply means more water changes (which you have been doing already) to keep toxins in check. It really should be quite easy for you so don't worry!

 

[Roz]

Thank you very much - you are such a fantastic help and I greatly appreciate it

 

[Roz]

Hello again, I have being changing 50% of my water daily and last night had a thought that the driftwood with little plant might be lowering the ph. I have removed that and will see if it has any effect!

The fishies are very perky in their super fresh water.

 

[jlk]

Glad to hear they are feeling better!