When I Do Water Changes, The Ph Is Still Below 7

[branjie]

Hi. I have a 100Litre tank which has been up and running for around 2 months. During the first 6 weeks or so, when I did water changes, the pH would go above 7, and I had to use a product called pH down to reduce it to 7. Now, whenever I do a water change, even if it's 50% new water, the pH doesn't go above about 6.5. Is this normal once a tank has been established for a while? The water looks clean. The filter looks a bit dirty, but it doesn't really look like it needs a clean yet to me. I thought I had to do a water change if the pH was below 7, but it's already been done? What's going on?

P.S No I don't have a master test kit, and yes the filter has been cleaned in the last couple of weeks.

 

[tiger~barbwire]

Hi. I have a 100Litre tank which has been up and running for around 2 months. During the first 6 weeks or so, when I did water changes, the pH would go above 7, and I had to use a product called pH down to reduce it to 7. Now, whenever I do a water change, even if it's 50% new water, the pH doesn't go above about 6.5. Is this normal once a tank has been established for a while? The water looks clean. The filter looks a bit dirty, but it doesn't really look like it needs a clean yet to me. I thought I had to do a water change if the pH was below 7, but it's already been done? What's going on?

P.S No I don't have a master test kit, and yes the filter has been cleaned in the last couple of weeks.

The PH of your tank doesnt nessacarily change if u do a water change. It would change though in the the water u are replacing and putting back into the tank is a different ph than your original water.
Also runaway or unstable ph may be occuring if your water is too soft-as in low in calcium,magnesium and other elements.

I recomend you get a water hardness test kit from your local aquarium or pet store to test your water.

 

[rdd1952]

As a general rule, the actual number of the pH is unimportant. The key is that it's stable. Most fish can easily adapt to a pH that is outside their optimal range. Using the pH adjusters is actually the worst thing you can do because it keeps your pH in a constant swing. The pH down may have lowered it to a point that it won't come back up without a large water change. Don't worry about that though as 6.5 is fine for most fish. All of the fish you have except for the mollies are perfectly at home in slightly acidic water like yours. Stop using the pH down and your pH should gradually come back to what it is from the tap. As for water changes, the main purpose for them is to remove nitrates and allow you to do some weekly cleaniing and gravel vacuuming.

And just a side note, keep a close eye on the betta, gourami and guppies. Generally, bettas and guppies don't work together because the betta sees the guppies fancy tail as another betta and will attack it. Bettas and gouramis are from the same family so bettas will usually attack them also. They could be fine for a while and then suddenly you have an all out battle that the betta will almost certainly win. And the BGK may eventually make a meal of some of your smaller fish if he isn't fed properly.

 

[Aphotic Phoenix]

Could be several things...
- The pH of your tap water can vary over time depending on the municipal water source...your tap water may now be a bit softer than it used to be.
- When you are testing the tanks pH. When water comes fresh out of the tap it often has a much high CO2 content than it would if you let it sit out for several hours. This is why to get an accurate reading of the pH tap you must let it sit out overnight to allow the CO2 to gas off. Mine goes from a pH of 7.4 to 8.2!!!
- Your water is quite soft already and the natural acids from waste products cause the pH to drop slightly naturally

Weekly water changes not only help to replace minerals absorbed by plants and fish, but also help remove acids and waste products that slowly cause the pH to drop. Furthermore, weekly water changes remove nitrates and the growth inhibiting hormones that some fish secrete that cause stunting and shortened lifespans. If you want to use one test as a "measure" on how much water to change I would suggest the NitrAte test because that one can really help you spot problems earlier.

 

[branjie]

O.K thanks for your help. I'll look into getting a Nitrate test. I think if I do weekly water changes, I'll be able to maintain the tank at around 6.5. I think I'll also clean my filter today, which will help keep the tank from getting too dirty before the next water change. I've bought a less powerful filter, and I'm finding it gets dirty more quickly. I'll cut back on the flakes at tea time as well, as the fish seem to focus on the frozen food, and the flakes get left sitting there. Thanks again.

Oh and I'm keeping a close eye on the compatability of my fish. I feed the Black Ghost very well. He is way too small to eat a Tetra at the moment, but I will look out for trouble when he gets bigger. So far the only fish my Betta has been interested in lunging at is my Gold Mollie. It's very half hearted though, he is very layed back. Still if trouble starts, someone will be removed from the tank.

 

[2day]

I have the same problem, but it is the opposite. Sydney water put loads of chlorine and upped the pH in our water, to an extent, and now my water out of the tap reads 8.0 - 8.2 (we had a big scare with bacteria from loads of rain). So i just leave my fish how they are, and their quite happy... But most of the times the pH decreases over time.

 

[tiger~barbwire]

same here choc

 

[fishlette]

seems we are pretty lucky i brisbane. tap water comes out 7.4 consistently and as far as other additives go, there are very few