High PH, large tank, low stock

[stuhyde]

Hi all
Tank has been running for 2 months now, I had 11 Neon Tetras in a 40L tank and was getting high PH then (was doing regular water changes, and had about 8-10 quite large plants in there.
Recently bought a 105L tank and have the same fish in.
The tap water is around 7.4, but after just one week it appears to have increased to as high as I can read on the API test kit (8.8).
I am running the regular light that came with the tank (Tetra Starter Line) have a double airstone and am using the filter from the old tank (was bought over spec to accommodate a bigger tank)
The substrate is silica based so should not change PH, I have 5-6 plants in there and no other decorations other than some plastic 'stones'.
The filter was set up using Nitrico and the fish and levels have been fine apart from this PH issue. Ammonia/Nitrates/Nitrites all 0 and have been for a while.

I have NOT touched the filter in 2 months since I started the first tank.

I am using a Nitrite filter on the tap water as our nitrite levels are around 40 from the tap, and then I just add the required level of tapsafe.
I have tried adding a 'leaf' as recommended by a LFS, but it's just the one and was told to get that for my then 40L tank.
There is a LOT of algae growth after just a week and I know this can be contributed to by the alkaline water.
Total hardness is 150ppm / Carbonate 80ppm which was tested using the paper strips as my API doesnt come with the others.

Any ideas?

 

[stuhyde]

 

[MattW]

It's a bit of a tricky thing to get right with newer aquariums. My 90L has had an algae problem since it was set up in late January this year. After many different things were altered and changed I found it was the lighting that mainly caused the alage issue (intensity and duration hours). I think @Essjay could help you here as she helped me with my water hardness issues a while back

 

[Essjay]

I've tried to find what your hardness (GH) is likely to be but unfortunately South Staffs Water won't load the map for me

Can you tell us exactly what your substrate is, please. You say it's silica based but a link to the product would help (it's just that I'm suspicious of the white bits). The usual cause of a rising pH is something made of calcium carbonate tank dissolving in the water - crushed coral in the substrate or limestone rocks for example.


Something you could try - find three tubs (old ice cream tubs or similar would be fine). Fill them all with tap water then put some of the substrate in one and one of those rocks in the photo in the second. Leave the third with just water. Test the pH next day, then again a few days later.
The tub with just water is the control to see what happens to the pH with nothing added to it. Compare the pH of all three tubs after a week. If either the substrate tub or the rock tub (or both) are higher than the just water tub, you've found the culprit.
However, if the just water tub pH has also risen, it's the water.

 

[stuhyde]

Hi Essjay
Substrate is this
I have tested some tap water that has been in a glass for 48hrs and it went from 7.0-7.4 .....

The 'rocks' are basically one piece of plastic (chosen by my 5yr old as it's essentially 'his' tank)...

 

[Essjay]

I see the pack says the substrate is inert but it's still worth testing just to eliminate it as the cause.

Try leaving some water to stand with some substrate in it, and some more water with one of the rocks in the tank in it. That'll show if it's substrate or rock that are causing it.

 

[stuhyde]

Here's the water report for my area

 

[stuhyde]

I've just tested the tap water I put into a glass 48hrs ago, it's at around 8.0. Tested fresh tap water again and its at around 6.8 - 7.0.....

 

[Essjay]

So the rise in pH is due to tap water gassing out on standing rather than something in the tank pushing it up. It is quite common for tap water to change pH on standing. Always compare tank water to tap water that's been allowed to stand and reach its natural pH rather than comparing it to freshly run tap water.



Looking at your water quality report -

They give a pH of average 6.97 with a range of the samples they tested from 6.8 to 7.4. This is lower than your water that's stood for 48 hours. I have no idea why the difference

Your hardness is 150 ppm and 9.5 dH (German degrees). You need to know the level in both units as some fish profiles give the hardness range in ppm while others give it in dH. This is middling water. Many soft water fish are fine in this hardness, but avoid those which must have very soft water. Some hard water fish will be OK but it's too soft for many hard water fish.

Tap water ammonia is very low, too low at 0.02 ppm for our testers to detect. Similarly for nitrite, our testers can't detect as low as 0.01 ppm. This suggest they use chlorine as a disinfectant rather than chloramine.

Nitrate is quite high at 33 ppm average - but you already know this since you use a nitrate filter for water changes.



Since GH is in the middling regions between soft and hard it is likely that KH will be similar. Unless KH is low it is hard to change pH, whether by adding chemicals or things like catappa leaves; the pH will drop immediately then bounce back and a swinging pH is worse for fish than a stable one which is perhaps a bit high. Leave the pH as it is and look for fish which have your hardness near the middle of their range.

 

[stuhyde]

So the rise in pH is due to tap water gassing out on standing rather than something in the tank pushing it up. It is quite common for tap water to change pH on standing. Always compare tank water to tap water that's been allowed to stand and reach its natural pH rather than comparing it to freshly run tap water.



Looking at your water quality report -

They give a pH of average 6.97 with a range of the samples they tested from 6.8 to 7.4. This is lower than your water that's stood for 48 hours. I have no idea why the difference

Your hardness is 150 ppm and 9.5 dH (German degrees). You need to know the level in both units as some fish profiles give the hardness range in ppm while others give it in dH. This is middling water. Many soft water fish are fine in this hardness, but avoid those which must have very soft water. Some hard water fish will be OK but it's too soft for many hard water fish.

Tap water ammonia is very low, too low at 0.02 ppm for our testers to detect. Similarly for nitrite, our testers can't detect as low as 0.01 ppm. This suggest they use chlorine as a disinfectant rather than chloramine.

Nitrate is quite high at 33 ppm average - but you already know this since you use a nitrate filter for water changes.



Since GH is in the middling regions between soft and hard it is likely that KH will be similar. Unless KH is low it is hard to change pH, whether by adding chemicals or things like catappa leaves; the pH will drop immediately then bounce back and a swinging pH is worse for fish than a stable one which is perhaps a bit high. Leave the pH as it is and look for fish which have your hardness near the middle of their range.

Thanks for the detailed response, appreciated!

Tonight we removed 20% of the water, and decided to test some of the white gravel bits. I scratched at a piece with a stanley knife and put vinegar on, but couldn't see any fizzing particular. I got some pliers on a piece and crushed it into dust. Putting vinegar on made it fizz like crazy!

So, we are in the process of doing a small water change each night whilst removing some gravel, so the pH difference isn't too startling/drastic for the fish as they didn't particularly seem to care about the 8.8pH! I don't think it would have done them much good long term, however!

Tested the (standing) water again tonight and it's looking to be around 8

Have put some gravel into a bowl with some fresh tap water as a test and will check that in a few days. It's currently about 7.0pH.

So it is looking like substrate is the culprit! Even though thousands of Amazon reviews never mentioned once about it causing a change in pH.

What substrate is recommended to 100% guarantee no change in pH so I can start looking around.

Thanks again so much!

 

[stuhyde]

They give a pH of average 6.97 with a range of the samples they tested from 6.8 to 7.4. This is lower than your water that's stood for 48 hours. I have no idea why the difference

But do they test it after 48hrs plus after it's left the tap?

 

[Essjay]

That's the question, they never say in the water quality reports.



I've always used 'natural' coloured substrate (ie shades of brown/beige), gravel at first then sand in later years. I've never had any problems with those affecting pH. It's mainly white which affects pH as white is often crushed coral or limestone both of which are calcium carbonate.

 

[stuhyde]

That's the question, they never say in the water quality reports.



I've always used 'natural' coloured substrate (ie shades of brown/beige), gravel at first then sand in later years. I've never had any problems with those affecting pH. It's mainly white which affects pH as white is often crushed coral or limestone both of which are calcium carbonate.

Yep, those white bit in there were super easy to crush as well. Every day's a school day.
I'll get some regular gravel for now then, do you think something like this would be suitable?

Paranoid about white bits now

 

[MattW]

I’ve used pea gravel before and never had any issues. But I filtered out any sharp bits and just used rounded gravel. You could have a look at b&q or a local garden centre which is what I did.

 

[Essjay]

I started with pea gravel, then found finer gravel so changed to that, then changed to sand. During lockdown I realised the sand was getting a bit thin and couldn't find the same brand on line to top up so bought a different brand which to me is more like micro gravel than sand. But all these have looked like your photo, just different sized particles.