Inert soil and low PH

[Shrimpmaster]

I normally use active soil like Ada or Glasgarten.

About a year ago I setup a few tanks with Inert soil. Dennerle Quartz. Simple black gravel.
I use the same water as in other tanks, Osmosis water plus minerals to boost GH.

What I don't get is that PH is dropping very low. Up tot PH 4.2. Shrimp don't seem to care and even breed normally. So I don't think I should add something to raise the KH so far.

More people who experience this?

 

[jayc]

That is  what's known as "old tank syndrome". 

Look it up. 

Clean filters,  vacuum substrate,  add a handful of crushed coral.

[Shrimpmaster]

I've read about that phenomenon, but seems not to apply on my tanks. Cause I do not a very small WC on a weekly basis.

But I might have done something else that will influence the PH. I've added a few alder cones a while ago. Maybe they do affect the PH more then I expected.

Also the active soil lowers the PH but also seems to buffer it some how that it will nog go too low. 

Removed the alder cones and will see what a WC will bring this weekend...

Thanks for thinking along with me

[daveron]

If your tanks are well maintained than this is really surprising. I have 3 tanks on inert soil, and in two of them I am keeping taiwan bee's and mischling so I need my pH to be slightly acidic - in both I need to either use peat, or active substrate as filter media to get pH levels down. If I would not the pH would slowly go back to 7.0 region.

Alder cones can lower pH but you would have to add really lots of them to lower the pH by at least 1 degree.

[jayc]

6 hours ago, Shrimpmaster said:

Cause I do not a very small WC on a weekly basis.

Removed the alder cones and will see what a WC will bring this weekend...

 

Yes, I'm sure you are good at keeping up with regular water changes... but have you done this ...

On 02/02/2017 at 7:42 AM, jayc said:

Clean filters,  vacuum substrate

When was the last time you cleaned your filter?

[Shrimpmaster]

The filters are not very dirty. The tanks are quite clear like the others, not much mess on the soil etc.

I don't know all about PH but I know it's more complex then only the number. Low PH with peat is different than low PH because of zero KH.

So today I measured 4.3. This is a small tank, netto about 20. So I've added some tap water, about 0,2 liters and it already reaised to 5.6PH, very quick btw. This is why it makes me wonder.

Shrimp are doing fine, so I will probaly keep going this way for these tanks. The others tanks I keep the active soil. 

[Shrimpmaster]

Update:

I guess I figure it out. So I added 2% tap water (gh13, KH7) and the PH spike to 6.0 in seconds, then I stopped adding the water. Next morning, wtf PH 4.5 :D. Added tap water again and it raised fast to 6.0 again. The next day, it was 5.3. Add a little tap water again etc.

Now I guess about 5 - 10% is tap water and the KH must be somewhere 1-3. The PH is stable now or gets lower very slow.

So it's probaly that simple. The KH buffers the PH as I already learned on school long ago and because of the Inert soil with Osmose water + minerals of GH6 and KH0, the PH could drop that low.

It was not really acid I guess, since I just needed a little tap water to raise it, but just because the lack of a buffer.

The active soil must do something like it, because I never saw a tank with active soil below PH5.5.

So when doing WC I just add a little tapwater from now on.