Hi! I haven't been on here for a while, but I'm having a few issues with the pH in the 75 gallon. I need it to be at a 6.5 or lower. Currently I've been trying using Waterlife pH 6.5 buffer, but it only barely drops the pH from its current 7.2, it goes down to like, 6.8 I believe. What would you suggest I try in order to lower the pH? Is there a different brand I could try? Thanks!
Keeping the pH down
- Thread starter ppetropulo
- Start date
Attempts to lower pH frequently fail, or are temporary at best. And fluctuating pH is more stressful and debilitating to fish than a steady pH that is not too far afield. And, one more detriment...all these chemicals going into the tank do affect the biology in various ways, and add TDS (total dissolved solids) which can be very harmful to some fish.
Before attempting any adjustment to pH, you must know the GH and KH of the water. This will be the source water, out of the tap (or well), and this is unlikely to change much in the aquarium unless something is being added that specifically targets it. And obviously this is another source of pH-affecting substances.
The KH (carbonate hardness) acts as a sort of buffer, to maintain a stable pH. The degree to which this works depends upon the KH level, and any attempt to lower the pH by any method (including peat, leaves, wood) other than diluting the water with "pure" water will be countering the buffering capacity of the KH.
So, if you can give us the GH (general hardness) and KH of your source water [this you should be able to ascertain from the municipal water folks, perhaps on their website, unless you are on a private well], it will be helpful.
Also, what is the reason you want 6.5? I assume for some particular fish. But 6.5 to 6.8 is miniscule to fish, and even the 7.2 may be perfectly acceptable. I appreciate the significance of above and below 7.0, so this may need some intervention depending upon the fish. But assuming the fish in question is soft water, hence wanting an acidic pH, the pH adjusting chemicals like Waterlife is going to actually be more harm than benefit. I can't say much more without knowing the specifics, being the fish species and GH/KH. Also, are live plants in the tank? And are there any calcareous substances? Both of these also play into the equation.
Byron.
Before attempting any adjustment to pH, you must know the GH and KH of the water. This will be the source water, out of the tap (or well), and this is unlikely to change much in the aquarium unless something is being added that specifically targets it. And obviously this is another source of pH-affecting substances.
The KH (carbonate hardness) acts as a sort of buffer, to maintain a stable pH. The degree to which this works depends upon the KH level, and any attempt to lower the pH by any method (including peat, leaves, wood) other than diluting the water with "pure" water will be countering the buffering capacity of the KH.
So, if you can give us the GH (general hardness) and KH of your source water [this you should be able to ascertain from the municipal water folks, perhaps on their website, unless you are on a private well], it will be helpful.
Also, what is the reason you want 6.5? I assume for some particular fish. But 6.5 to 6.8 is miniscule to fish, and even the 7.2 may be perfectly acceptable. I appreciate the significance of above and below 7.0, so this may need some intervention depending upon the fish. But assuming the fish in question is soft water, hence wanting an acidic pH, the pH adjusting chemicals like Waterlife is going to actually be more harm than benefit. I can't say much more without knowing the specifics, being the fish species and GH/KH. Also, are live plants in the tank? And are there any calcareous substances? Both of these also play into the equation.
Byron.
I'd be leery of using acids to lower ph. They can be harmful and often because of buffering compounds in the water the ph will rebound right back where it started. If your KH is much above 3 you'll likely have an issue trying to keep the ph below 7. If I may ask, why do you need the ph at 6.5? The difference between the two values for the majority of fauna will be insignificant.
If 6.5 is an absolute must, find out what the KH is. You may need to soften the water through RO or DI and mix with your normal water to achieve a KH in the vicinity of 3. Then use peat or driftwood to naturally acidify the water to the desired ph. It will take some tinkering with the amount of peat to keep the water at a desired ph. Also, new water for partials will need to be adjusted prior to introducing it into the tank to avoid shocking the fish. Softening the water through RO/DI will also lower GH and a large, rapid change in hardness can cause lethal shock.
Mark
If 6.5 is an absolute must, find out what the KH is. You may need to soften the water through RO or DI and mix with your normal water to achieve a KH in the vicinity of 3. Then use peat or driftwood to naturally acidify the water to the desired ph. It will take some tinkering with the amount of peat to keep the water at a desired ph. Also, new water for partials will need to be adjusted prior to introducing it into the tank to avoid shocking the fish. Softening the water through RO/DI will also lower GH and a large, rapid change in hardness can cause lethal shock.
Mark
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Okay, I've never had to measure the Kh of the water before, so how should I go about doing that? Is there a specific test kit? Also the reason for the adjustment is for the South American fish I wish to keep... the only time I was able to keep them long term succesfully was when the tank was constantly kept below 7.0. I then changed the tank though, raised the pH, and got different fish. I'd like to go back though, however it is proving quite difficult. 
6.5 isn't exactly the necessary place for it to be, I just would like it to be there because it suits the various fish. Yes, there are a few live plants in the tank, mostly java ferns and anubias, and I don't believe there are any particularly calcareous substances, except a piece of shale.
6.5 isn't exactly the necessary place for it to be, I just would like it to be there because it suits the various fish. Yes, there are a few live plants in the tank, mostly java ferns and anubias, and I don't believe there are any particularly calcareous substances, except a piece of shale.
Before spending money on a test kit [and the API is a good one if you do] I would check with your municipal water supply people. Many have a website, and this may be stated, or they should be able to tell you if you ask. If you find a website but can't fathom the data [this can be under various names, like Alkalinity, bicarbonate, etc), post the link and one of us can take a look.Okay, I've never had to measure the Kh of the water before, so how should I go about doing that? Is there a specific test kit? Also the reason for the adjustment is for the South American fish I wish to keep... the only time I was able to keep them long term succesfully was when the tank was constantly kept below 7.0. I then changed the tank though, raised the pH, and got different fish. I'd like to go back though, however it is proving quite difficult.
KH has no effect on fish, but as I mentioned previously it does buffer the pH, or work to keep it stable. Knowing the KH will simply tell you and us how much effort is going to be needed to lower the pH.
The breakdown of organics by bacteria in the substrate is the major source of natural CO2 in an aquarium, and CO2 will acidify the water, thus lowering pH. But again the KH may counter this. The easiest and safest way to lower KH is by diluting the water with "pure" water like RO or distilled or rainwater/snowmelt. But before we venture into this, knowing the KH is essential. In my situation with near-zero KH, the tap water pH of 7 or 7.2 lowers to anywhere from below 6 to 6.4 depending upon the aquarium; each is biologically unique according to the fish load, amount of wood, leaves, plants, etc.
Shale is not calcareous, so no issue there. Marble, dolomite, limestone, lava, coral, shells are all calcareous.
To the fish. There are many South American fish that will be fine at a pH around 7.0 but without knowing the species I can't say more. You shouldn't have issues with most if you can achieve a pH just under 7, or even above with many. The GH is actually the more important of the two (GH and pH). You haven't mentioned GH yet; again, this the water folks should have.
Byron.
