PH and sand substrate

[julielynn47]

So today I was doing water changes and decided to check the ph in both tanks. I want to move my fish from the 55 to 75 as mentioned in another thread

I use the same water, same sink, same everything and the ph is lower in the 55 than in the 75.

After some thought and another round of testing, it dawned on me that the substrates are different. The 55 has a gravel substrate. The 75 has a sand substrate. This is the only difference. So I have to just assume it is due to the different substrates.

But what do I do in order to be able to move the fish? PH matters a lot I know. I have cories in both tanks and they are doing fine in both tanks. But I am afraid that the change in ph will hurt the ones I am transferring.

The PH in the destination tank...75 gallon is around 7.4. The PH in the 55 is around 6.8.

Am I right is thinking that this is a big difference? Will this hurt the fish ? If so, how do I fix it?

 

[seangee]

Tanks can have a tendency to become more acidic over time for a number of reasons. As long as your pH is stable over 24-48 hours in the new tank (test at the same time of day) your fish will be fine. If you tested the new tank immediately after filling test again after 24 hours. Water companies often adjust the pH temporarily to avoid corroding the pipes. If you leave the water for 24 hours it should return to its "natural" level.

 

[julielynn47]

It is just weird to me that the ph in both tanks would be so different.

 

[Byron]

It is just weird to me that the ph in both tanks would be so different.

There is a reason but it depends upon factors. As seangee mentioned, over time the pH will tend to lower as the organics breakdown acidifies the water. However, other factors play into this; the initial GH and KH of the source water (or tank water if different), the amount of CO2 dissolved in the water, and any "buffering" items such as calcareous substrate material, rock (calcareous), coral, shells, etc.

The first thing is to know the source water parameters, being GH, KH and pH. The GH and KH if high will indicate a stronger buffer on pH, which means they will work to prevent fluctuations at least up until they no longer have the capability--which again depends upon their initial numbers.

I have several tanks in my fish room and even with the same water, similar fish and plant loads, same maintenance...the pH will vary depending upon the individual tank's biological system. However, as I have no buffering at all, the pH does lower in all tanks, though to different levels. When I set up a new tank, as I did when I moved, the pH was around 7.2 compared to the tanks which run from 5 (or below likely) up to 6's depending. This was due to the pH of the source water which is 7.2 due to the addition of soda ash by the water authority, and this dissipates out quickly so the pH began to lower after a day. Once fish were present, it lowered further.

The difference between 6.8 and 7.4 is not that much in terms of the actual number, but here the issue is more that it is slightly acidic at 6.8 and slightly basic at 7.4 so I would let the new tank (the 7.4) run (filter, heater, light if planted) for a day or two and see what happens. Just being overly cautious.

 

[julielynn47]

Okay. The tank, 75 gallon, is not new, but will be new to these fish. I will just wait and check it again tomorrow

Will this difference in PH harm the fish if it does not change?

 

[Byron]

Okay. The tank, 75 gallon, is not new, but will be new to these fish. I will just wait and check it again tomorrow

Will this difference in PH harm the fish if it does not change?

No, it shouldn't here. A one-time change of up to 1 full degree (say, 6.6 to 7.6) can be handled by most fish except very delicate species, though it is something we want to avoid if we can. It is repeated fluctuating pH over a 24 hour period back and forth such as can occur when aquarists keep trying to lower or raise the pH with chemicals--this can often result in permanent internal damage, stress, and even death. Given that both tanks are running, I would check the pH tomorrow and see what it is doing, and maybe the next day too. You're presumably in no hurry. Remember to test pH at the same time each day to ensure a more accurate reading, there is a diurnal pH shift ever 24 hours in nature and in aquaria, especially with live plants. This is primarily due to the CO2 change from day to night and back again. So a reading of say 6.8 in the morning might become 7.2 by the end of the day, then revert back over night.

 

[julielynn47]

Okay thanks! I will just watch it for a few days and see what happens