pH drop in established tank

[Micko50]

Hello,

Wondering if anyone can help me with my problem with my pH. My pH levels have dropped significantly over the last 6-8 weeks. I bought a digital pH reader and the last reading was 5.2. It was always around 7.5 previously. I have noticed the tetras and barbs in particular now hang around the corner of my tank and stay there - something they didn't do before. No deaths and are eating well, just a change in their behaviour. My other fish are fine.

My water provider has a pH of 7.5, a 4.4 KH and 4-8 GH.

I do a weekly water change of 30-50%.

I did inherit a friend's fish collection, which I had to take but means my tank is definitely overstocked. The extra fish added coincide with the pH drop.

It's a relatively heavy planted tank, my ammonia readings are between 0 - 0.25, 0 Nitrates and 0 Nitrites.

Any permanent solutions or suggestions?

I don't want to add buffers or baking soda as it's not a long term solution. I've removed my driftwood.

I'm considering adding crushed coral or limestone, even though it's not recommended in a tropical tank.

Or do I have to get a bigger pump or add an air stone to add more oxygen?

Any help or advice would be great!

 

[Circus]

If you have measurable ammonia, it is possible the added bioload is putting your tank through another cycle. My biggest suggestion for problems is always large water changes first.

 

[itiwhetu]

How much plant do you have ( around 30-50% of the volume). Do you have a natural base in the tank. It was a good idea to remove the wood. Are you sure of the pH of the provided water. 5.2 is low and will take sometime to get it up in the mid 6's make sure you continue with the 30% water changes weekly and maybe do an extra one during the week.

 

[itiwhetu]

Watch large water changes you don't want to pH shock your fish

 

[Micko50]

I have been doing the water changes every week and it goes up with the fresh water and 4-5 days later it's back in the low 5's. I have tested my water source and it was 7.4pH

The planted tank would be around 35% of the volume.

 

[itiwhetu]

I sort of like the idea of some limestone in your tank as a buffer. It will lift your hardness as well

 

[Colin_T]

Test your tap water so you know exactly what the pH, GH and KH are.

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You can add shells, dead coral rubble, limestone or sandstone to any aquarium if you are having trouble with the pH dropping. We had limestone in every tank in the shop to keep the pH stable.

Add a bit of limestone and monitor the pH over a week. If it drops, then add another bit and monitor for a week. Continue adding a bit and monitoring until the pH settles at 7.0 or wherever you want it.

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If your pH is dropping over a 4-5 day period, your nitrate is probably going up rapidly too. You need to do more frequent water changes and bigger water changes. However, don't do big water changes until the pH is back up to normal.

I would do a 30% water change and gravel clean every day for a week or two. When the pH of the aquarium water is similar to the tap water, then do a 75% water change and gravel clean every couple of days.

If you get some limestone, shells or coral rubble in the tank and the pH settles around 7.5, then do a 75% water change and gravel clean twice a week until you rehome some of the surplus fish.

 

[seangee]

What are your other fish? Tetras and barbs do better in low pH anyway.
Digital testers do require periodic calibration - so it is possible that it is just the tester.

 

[Micko50]

Test your tap water so you know exactly what the pH, GH and KH are.

--------------------
You can add shells, dead coral rubble, limestone or sandstone to any aquarium if you are having trouble with the pH dropping. We had limestone in every tank in the shop to keep the pH stable.

Add a bit of limestone and monitor the pH over a week. If it drops, then add another bit and monitor for a week. Continue adding a bit and monitoring until the pH settles at 7.0 or wherever you want it.

--------------------
If your pH is dropping over a 4-5 day period, your nitrate is probably going up rapidly too. You need to do more frequent water changes and bigger water changes. However, don't do big water changes until the pH is back up to normal.

I would do a 30% water change and gravel clean every day for a week or two. When the pH of the aquarium water is similar to the tap water, then do a 75% water change and gravel clean every couple of days.

If you get some limestone, shells or coral rubble in the tank and the pH settles around 7.5, then do a 75% water change and gravel clean twice a week until you rehome some of the surplus fish.

Thanks for that, I’ll do that and see how it goes

 

[Micko50]

What are your other fish? Tetras and barbs do better in low pH anyway.
Digital testers do require periodic calibration - so it is possible that it is just the tester.

I have dwarf and regular gouramis, pleccos, ottos, 2 Bolivian rams and 3 clown loach.

the tester is new and was calibrated at the store

 

[Avel1896]

My water provider has a pH of 7.5, a 4.4 KH and 4-8 GH.

Hello,
what volume is your tank ? A picture would be helpful.

I do a weekly water change of 30-50%.

Too much to me.
10-15% would be better. As NH2 and NH3 are 0 try to water change 10% every 10 days and see how it goes.
Tretras and Barbs (wich ones precisely) dislike very acidic water. They do better with pH 7-7.3
pH 5.2 is also too low for your other fishes, even is they can tolerate it.

Or do I have to get a bigger pump or add an air stone to add more oxygen?

How big is your pump ? I mean how many litres/h ? Any eddies/wirls at the surface ?

 

[Micko50]

Hello,
what volume is your tank ? A picture would be helpful.


Too much to me.
10-15% would be better. As NH2 and NH3 are 0 try to water change 10% every 10 days and see how it goes.
Tretras and Barbs (wich ones precisely) dislike very acidic water. They do better with pH 7-7.3
pH 5.2 is also too low for your other fishes, even is they can tolerate it.


How big is your pump ? I mean how many litres/h ? Any eddies/wirls at the surface ?

It’s a 180L (approx 130 after plants, decorations and substrate) with a 600 l/hr pump. Gives a slight disturbance if the surface

 

[Avel1896]

You might place outlet pipe (including the spray bar) ABOVE the surface of the water to increase disturbance which will help to increase pH.
About water change do only 10%. As NH2 and NH3 are 0 try to water change every 10 days, even 15 days and see how it goes. Don't forget to check NO2 NO3.
What do you use, frops or stripes ?

 

[seangee]

Too much to me.
10-15% would be better. As NH2 and NH3 are 0 try to water change 10% every 10 days and see how it goes.
Tretras and Barbs (wich ones precisely) dislike very acidic water. They do better with pH 7-7.3
pH 5.2 is also too low for your other fishes, even is they can tolerate it.

This conflicts with most current recommendations to change at least 50% per week. Personally I change 75% even though I consistently have 0 N02 and NO3. The easiest way to ensure stability is to bring your tank closer to your tap every week. (There are lots of other reasons). My tanks are stable even though my KH is 0. Check your exact species on seriouslyfish.com, but most tetras and barbs do best in the range of 5-7pH.

 

[Avel1896]

To each their own.
I'd water change 50% only in case of NO2 NO3 dangerous increase.