Why Does The Ph Vary In 2 Different Tanks?

[alysonpeaches]

My tapwater pH is 7. The water in my Mark I tank is pH 7.5-8 today. It is usually about the same. The water in my Mark II tank is pH 5.5, it varies between 6 and 6.8 usually. I tested them both at same time 1630 pm.

Do different stones and gravel in different tanks make the difference? They both have plants. The Mark I tank is more mature than the Mark II.

 

[Loony Fish]

i think it's the rocks. bog wood will lower a pH and some rocks raise a pH

 

[Ace Of Spades]

i think it's the rocks. bog wood will lower a pH and some rocks raise a pH

Its likley the rocks are buffering the water or the gravel and the wood is lowering the PH. What fish have you got in each tank?

 

[Colin_T]

Besides rocks and wood which has already been mentioned, it can be the number of fishes in each tank or the amount of food going into each tank. The more food the more waste and the more ammonia produced. This in turn will create more nitric acid that will lower the PH. Bigger fish also eat more and produce more waste thus causing the PH to drop quicker.
You should check the nitrates and see if one tank has a higher nitrate reading.
Also do the same size water change on both tanks. It might be one tank gets a bigger water change than the other. This will dilute the nutrients and help bring the PH back up.

 

[alysonpeaches]

Besides rocks and wood which has already been mentioned, it can be the number of fishes in each tank or the amount of food going into each tank. The more food the more waste and the more ammonia produced. This in turn will create more nitric acid that will lower the PH. Bigger fish also eat more and produce more waste thus causing the PH to drop quicker.
You should check the nitrates and see if one tank has a higher nitrate reading.
Also do the same size water change on both tanks. It might be one tank gets a bigger water change than the other. This will dilute the nutrients and help bring the PH back up.

There is more wood in the Mark I tank which has the higher pH, but more stones in the Mark II tank. The gravel is natural pea gravel in the Mark I but in the Mark II I have some Roman Gravel which is "Made from silica aggregates known for their inert properties and coated in a colourfast resin for trouble free fish keeping, this gravel is suitable for all types of aquarium set-ups including coldwater, tropical and saltwater, and is also the perfect planting medium due to its finer size. Suitable for bottom feeders and barbed fish, it will not change the PH of the water.'
Fish in Mark I
1 Bristlenose
5 albino cory
6 neon tetra
3 platy
6 danio

Fish in Mark II
8 adult platy
4 young platy
5 young male endler

I did the same size water change in both last Tuesday. I will be doing it again this Tuesday,

Full water stats:
Mark I
Nitrite less than 0.25ppm
Ammonia 0
pH 7.5 - 8
NitrAte 5 ppm
This tank has hair algae on uppermost leaves

Mark II
Ammonia 0
Nitrite 0
NitrAte 0 or less than 5 ppm
pH 5.5

Still confused.

 

[Colin_T]

take a sample of your tap water to the LFS and have the KH (carbonate hardness) checked. If the KH is low then the PH will drop rapidly and that would mean there is something in one tank that is causing the PH to go up.

Most gravel is fine and pea gravel is not going to change the PH. Shell, limestone and coral/ coral rubble will raise the PH.
Driftwood normally lowers the PH but I had a ppiece from the beach that raised my tank water PH to about 8.0. I assumed it was because the would had been in the ocean for a while and absorbed a lot if minerals, but I can't be certain.

 

[alysonpeaches]

take a sample of your tap water to the LFS and have the KH (carbonate hardness) checked. If the KH is low then the PH will drop rapidly and that would mean there is something in one tank that is causing the PH to go up.

Most gravel is fine and pea gravel is not going to change the PH. Shell, limestone and coral/ coral rubble will raise the PH.
Driftwood normally lowers the PH but I had a ppiece from the beach that raised my tank water PH to about 8.0. I assumed it was because the would had been in the ocean for a while and absorbed a lot if minerals, but I can't be certain.

When I first set up the tank the KH was 40. Is it likely to vary?

 

[Colin_T]

The KH of the mains water should not vary unless the water source is coming from somewhere else.
A KH of 40ppm is pretty low, perhaps try buffering it up a bit. You can use sodium bicarbonate, available from any supermarket. Add a little bit each day but not too much otherwise the PH will go right up. Most petshops sell products like "PH UP", which is the same stuff but packaged differently and usually costs a lot more.
If you can get the KH up to about 100-150ppm then it should help stop the PH dropping as quickly.

 

[rabbut]

As Colin says, the KH is low. The important thing with pH usualy is that is is stable, more than it being in the ideal range. Extrem measurements though do need rectfying. I would personally consider a pH of less than 6.5 an extream measurement, unless you are specifically targeting a lower pH for breeding. Idealy IMO the pH in your mark II tank would be higher, but if the fish aren't looking in trouble, I'd leave the pH well alone If they look "off colour" in any way, you want to bring the pH up. It is important to know the chemistory behind the tanks pH level before you try to adjust it, as if you raise it without knowing what you are doing, the pH will fluctuate, and this will be worse for the fish than a "crashed" pH Some medications can also lower the pH. Have you treated this tank recently?

A tanks pH, KH and CO2 levels are all linked. pH is a measure of how acid or alkaline your water is. KH is the alcalinity of the water (not to be confused with the word alkaline as that is different ) and is a measure of how much acidity the water can take before the pH drops. CO2 is acidic and will lower the pH, usualy without moving the KH. Other acidic compounds (nitrate, nitrite e.t.c) will also lower the pH, but before they do, they will "use up the KH" i.e. the KH bonds with the acidic compounds to reduce their acitity and thus reduce their effects on the pH.

Unless you are injecting CO2, the levels of this compound will be low assuming good surface agitation, so for the pH to be low, so must the KH or the acidic chemicals in your tank have build-up due to poor maintanance. You do regular waterchanges, and the nitrate in the tank is low, so the latter is unlikely What test kit do you use?

To raise KH on a long-term basis, use crushed coral, about a plam full for every 20l of water and add it to the filter. It will disolve away with time adding KH. Rince the coral gravel under the tap at each filter clean (but not the rest of the filter media ) to remove any bacteria on it's surface, as the bacteria will stop it from disolving. Idealy, you would have two bags of coral gravel, and would rotate in a dry bag at each filter clean. The coral gravel is more cost effective than bicarbonate of soda, and will hold the pH more stable also, so all in all, is a better choice. Add the coral slowly though to avoid the pH raising too fast.

On a side note, test strips aren't accurate, so if these are what you are using, I'd speculate that the pH and KH aren't what the strips tell them to be. Liquid regent based test kits are more accurate

HTH, and sorry if that was a bit baffeling for this time on a morning
Rabbut

 

[alysonpeaches]

As Colin says, the KH is low. The important thing with pH usualy is that is is stable, more than it being in the ideal range. Extrem measurements though do need rectfying. I would personally consider a pH of less than 6.5 an extream measurement, unless you are specifically targeting a lower pH for breeding. Idealy IMO the pH in your mark II tank would be higher, but if the fish aren't looking in trouble, I'd leave the pH well alone If they look "off colour" in any way, you want to bring the pH up. It is important to know the chemistory behind the tanks pH level before you try to adjust it, as if you raise it without knowing what you are doing, the pH will fluctuate, and this will be worse for the fish than a "crashed" pH Some medications can also lower the pH. Have you treated this tank recently?

A tanks pH, KH and CO2 levels are all linked. pH is a measure of how acid or alkaline your water is. KH is the alcalinity of the water (not to be confused with the word alkaline as that is different ) and is a measure of how much acidity the water can take before the pH drops. CO2 is acidic and will lower the pH, usualy without moving the KH. Other acidic compounds (nitrate, nitrite e.t.c) will also lower the pH, but before they do, they will "use up the KH" i.e. the KH bonds with the acidic compounds to reduce their acitity and thus reduce their effects on the pH.

Unless you are injecting CO2, the levels of this compound will be low assuming good surface agitation, so for the pH to be low, so must the KH or the acidic chemicals in your tank have build-up due to poor maintanance. You do regular waterchanges, and the nitrate in the tank is low, so the latter is unlikely What test kit do you use?

To raise KH on a long-term basis, use crushed coral, about a plam full for every 20l of water and add it to the filter. It will disolve away with time adding KH. Rince the coral gravel under the tap at each filter clean (but not the rest of the filter media ) to remove any bacteria on it's surface, as the bacteria will stop it from disolving. Idealy, you would have two bags of coral gravel, and would rotate in a dry bag at each filter clean. The coral gravel is more cost effective than bicarbonate of soda, and will hold the pH more stable also, so all in all, is a better choice. Add the coral slowly though to avoid the pH raising too fast.

On a side note, test strips aren't accurate, so if these are what you are using, I'd speculate that the pH and KH aren't what the strips tell them to be. Liquid regent based test kits are more accurate

HTH, and sorry if that was a bit baffeling for this time on a morning
Rabbut

Test kit.

Ive a Nutrafin Mini Master Test kit, but I prefer the API individual tests (dropper type) for Ammonia and Nitrite. I also have another dropper type pH test but I cant remember the make. I dont use dip stick tests as I know they are inaccurate.

I have left things as they are for the moment cos I cant decide whether to leave it or not. They fish seem happy in the mark II tank with the lower pH. Im a bit busy messing about with the mark I tank (which has the higher pH) as I think there is whitespot.

 

[Colin_T]

if you just want to raise the PH a bit then add a bit of limestone, some shells or coral rubble like rabbut suggested. Monitor the PH and if it hasn't gone up enough then add a bit more shell. Once you get the right amount in the tank then the PH will pretty much stay there.

 

[alysonpeaches]

if you just want to raise the PH a bit then add a bit of limestone, some shells or coral rubble like rabbut suggested. Monitor the PH and if it hasn't gone up enough then add a bit more shell. Once you get the right amount in the tank then the PH will pretty much stay there.

Any type of shells Colin?