Can Plant Substrates Affect Water Readings

[soybean]

The water from my tap is Ph 7-7.5ish and is low in nitrates.

A couple of days after water changes, my tank ph rises to 8+, and the nitrates to almost 50mg/l. I think it is making some of my fish unwell and could be the reason I've lost some. Amm and Nitrite are 0.

The tank is moderately planted and has three pieces of wood. It has some rocks that I added a couple of weeks ago, but these ph and nitrate problems have been occuring since I set the tank up back in March. I tested them with vinegar before adding them, anyway.

The only difference between this set-up and the one I had before in a smaller tank is that I've added plant substrate under the gravel this time. I have the same wood, same brand of gravel (though it was new), same plants, same pebbles.

Could the substrate be the cause of my high nitrate and ph? My corys are pretty vigourous cleaners and it is starting to mix in with the gravel and larger particles are reaching the surface. I have to be really careful during gravel vacs not to suck it all up. If I move/remove a plant or any slightly buried decor the stuff plumes out the gravel and the water goes cloudy, which can't be good. I've been thinking of changing over to sand and the only thing stopping me is that the plant substrate wasn't cheap (same stuff the LFS used in its plant display tanks) but if it causing problems with the readings and therefore the fish, I'll be getting rid of it straight away.

 

[RadaR]

Firstly, nitrate test kits (even the liquid ones) are consistently innaccurate. They're better off in the bin.
Secondly, we'd really need to know the name of the plant substrate.
Most planted substrates will decrease pH and KH, not the other way around (with the exception of Eco-complete).
Let assume the nitrate is 50. This wont be harming your fish so you can rule that out. pH swings aren't in themselves harmful. It's rather the cause of the pH swing that is doing the damage. Folks just see the pH change and point the finger without realising it's what has caused the pH to change that is harmful to the fish.
Sufficient flow/circulation (10x volume of the tank turned over every hour) negates the need to gravel vac. Maybe a hoover every now and then.
I'd be doing small water 10% water changes per day after the tank lights go off and observe from there.

 

[soybean]

Sorry, I can't for the life of me remember the name of it. It came in a yellow tub and was mainly written on in German I think. "Something" Professional, maybe.

I know some fish that are sensitive to ph swings which is why I'd like to figure out what's raising it. The only thing I could think of that was different in this tank compared to my old one is this plant substrate, but I take it that's unlikely the cause.

I don't do gravel vacs that often, certainly not every water change, I have an army of shrimp that keep it relatively clean. I think I do a light one about once a fortnight, if that, more out of a habit than necessity. It bothered me how much of the substrate it disturbs, so I don't bother as much.

Well, something's raising the ph, I guess the mystery continues.

 

[RadaR]

This one.
Or this one?

 

[soybean]

First one, Deponit Mix.

 

[RadaR]

It shouldn't be effecting pH then.
Hhhmm, how strange.

 

[ian]

what is that rock on the left hand side of the aquarium?

 

[soybean]

what is that rock on the left hand side of the aquarium?

Just some pieces of rock making a cave. They've only been in a couple of weeks, the ph issue has been going on months.

Edit: Actually the left and in the middle is wood, the rocks are on the right side.

 

[StandbySetting]

How long are you leaving the tap water before testing it? My guess is you're doing it within a few hours of obtaining it, the tap water will still contain carbonic acid due to the high concentrations of CO[sub]2[/sub] that are dissolved into it to prolong the life of the water pipes.

Take a sample, and leave it in an open topped inert container, then test it after 24 hours.

 

[soybean]

How long are you leaving the tap water before testing it? My guess is you're doing it within a few hours of obtaining it, the tap water will still contain carbonic acid due to the high concentrations of CO[sub]2[/sub] that are dissolved into it to prolong the life of the water pipes.

Take a sample, and leave it in an open topped inert container, then test it after 24 hours.

I have tried that, ph stays around 7/7.5. The ph of the tank is rising a couple of days after a water change.

 

[StandbySetting]

Then something is buffering the PH, please can you run through all hard scape? What type of rock are you using? What is in the filter?

 

[soybean]

I don't know what kind of rock it is. I just bought a few pieces from the LFS. Gave it a good scrub and soak, didn't fizz under vinegar. Like I said, the ph issue has been going on since long before I added the rocks anyway.

DeponitMix plant substrate.
Standard black aquarium gravel from Pets at Home - have used this for years in other tanks with no ph problems.
Small amount of aquarium sand at the front of the tank.
Two large/1 small pieces of wood.

Filter is standard Juwel internal (Rio 180), still on the hunt for an external that I can both afford and will actually fit in the new style Juwel cabinet. Blue/white sponges and poly filter. No carbon.

 

[TwoTankAmin]

Small amount of aquarium sand at the front of the tank.

What brand/type? Some "aquarium sand" will raise pH.

 

[soybean]

Small amount of aquarium sand at the front of the tank.

What brand/type? Some "aquarium sand" will raise pH.

It doesn't seem too different from standard 'play sand'.

 

[ATK!!!]

May I ask, why does eco-complete raise the pH/kH? I just want to know before I buy it. If you could describe the rocks then that may help...