How do I stabilise pH?

[parkap]

Hi,

How do I keep my pH from dropping? I do a 35% water change and it drops back down below 6 straight away even though my tap water is basically neutral. I've put a bag of shell grit in the water in the filter unit, I've heard that helps to stabilise the pH. (Perhaps more would help.)

I've also read that kH is core to managing pH. If so, how do you manage kH then?

Any help much appreciated.

Regards,

p.

[Nigel]

The best way is with a KH buffer there is plenty of advise on this in the FAQ section of the forum.

[noyd]

I use Seachem products (the Tang one) to buffer the tank to a certain pH at each water change with limestone's in the tank to help keep the pH above 8.5 at all times. It work's for me, along with the Seachem lake salt.

My fish seem to love it and I'm getting stacks of spawns happening.

Good luck.

[Daniel]

Yep, its just a matter of increasing your carbonate hardness (kh) which is measured in degrees hardness or ppm. I find my tap water has a kh of 1.5 german degrees and I add a little sodium bicarbonate (bicarb soda) to get it up to 4 to 5 degrees. For African Rift lakers, you might need to get it to 12 degrees or more (12 degrees = 213ppm).

[AzFish]

Correct. KH will stabilize PH. Bi carb soda is a good way to increase KH but dont use it to maintain your KH, you will need to add some Limestone, crushed marble, crushed coral ect, what this does is when your PH drops under a certain figure ( dont have the actuals on hand at work, from memory its something like 7.8 before crushed marble dissolves) the acid in the water dissolves the carbonate and stabilizes the PH.

what sort of substate are you using? it may be worth changing it too crushed marble or crushed coral...

[parkap]

Correct. KH will stabilize PH. Bi carb soda is a good way to increase KH but dont use it to maintain your KH, you will need to add some Limestone, crushed marble, crushed coral ect, what this does is when your PH drops under a certain figure ( dont have the actuals on hand at work, from memory its something like 7.8 before crushed marble dissolves) the acid in the water dissolves the carbonate and stabilizes the PH.

what sort of substate are you using? it may be worth changing it too crushed marble or crushed coral...

←

I've just got a standard aquarium gravel substrate. Am trying to get the pH to stay around 6.5-7 for apistogrammas.

[steph]

Hi Parkap

How low is it dropping? Most apisto's wont mind a pH of <6. Some even require <5 to spawn and most people have problems getting that. Ideally for Apisto's I would shoot for 6 - 6.5pH

I suggest adding a tiny bit of bicarb (sodium bicarbonate) each day until your pH settles and you may have to treat your water before you add it in a water change each time. If you buffer the tank too much the Apisto's wont like it at all, as they are pretty particular about carbonate hardness (kH) or TDS (total dissolved solids) or conductivity or whatever else those rift lake fishies like.

The other thing to try is the Seachem Acid buffer which may help you get a stable but not high pH.

HTH

Steph

[Daniel]

Agree with Steph that you should try a small amount of bicarb soda each day until you get your kh up a little. Or even better, do it with your water change. But be careful not to use too much ine one go. Your ph will increase a little, however if you get your kh to around 4 degrees, the apistos wil be happy (despite a ph of 7 or more) becuase the water will still be soft. I have the pleasure of owning an aquamedic ph controller and just by chance I happen to be doing some tests with bicarb soda and Seachem Acid buffer over the past few days. The result is that bicarb soda works by approximately the following formula. One teaspoon (6 grams) added to 50 litres water will increase kh by 4 degrees ( in my case this results in an increase of my tap waters 7.6ph up to 8.0ph. What prompted me to do thse test is partly to do with suspicions I've had of Seachem's Acid buffer, which I have been using for some time. I do not have the results yet, but it appears that Seachem Acid buffer has a remendous affect on lowering ph initially, but then gradualy over the next 24 hours the ph increases substantially.

[parkap]

Daniel,

Last time my pH dropped so much I put in some pH up (purchased from one of my LFS's, which I guess is jsut over-priced bi-carb). I put in about 7 teaspoons (in a 650ltr tank), which is less than the amounts you've mentioned but the pH went from below 6 (both my current my test kits only go down to 6) to about 7.4, from memory. Something I thought might put my fish into shock. Strange that your tests show a much lower rise in pH from a higher dosage. But I'm guessing from what I've read recently and the advise I've received so far, that might then have to do with the different kH levels. Would that be correct?

p.

[Skyedge]

Parkap,

There must be something in your tank that is causing the PH to drop to that low.

I do not use any chemical buffer, because I don't want to turn my tanks into chemical cocktail. Hence my suggestion here is very traditional approach:

1. How often do you do the water change..?

2. Do you have any driftwood or plants or anything that releases something acidic..?

3. How old is your PH tester..? is it still giving you the right reading..?

Hope this helps

[parkap]

Skyedge,

Water changes - ahh my nemesis. But am getting better. Am trying to get 30% done each fortnight, ie. not many inhabitants in my tank at the moment at all. (Am also trying to get motivated to to 30% water change every weekend now as well.) But the pH falls immediately after the water changes in any case.

But yes, there's driftwood and it's very heavily planted. How do these effect the pH, I didn't realise they did?

pH testers (different brands): One a bit old and a brand new one - both give the same results.

I also am not keen to put chemicals in the water, hence putting in shell grit. But that's taking a while to have any effect, although I am going to put more in.

Regards,

p.

[Brett4Perth]

Hi Parkap,

If your pH is falling, first check for ammonia/nitrites/nitrates, but these are unlikely to be the cause in a low stocked, heavily planted tank.

Next check your water (presumably from the tap), but only after you have airiated it for 24 hours to allow the pH to stabilise.

If there is a substantial difference in the tap water and the tank water then something in the tank is leaching acids. This could well be your wood, which leach tannins that are acidic. If the wood has not been submerged for a long period of time (many months), then this could be the problem. Consider other decor. Are you adding anything else to the tank, dechlorinators, etc. Many of these are not pH neutral.

It is unlikely to be your plants, which tend not to alter pH, unless there is a lot of decomposing leaves, etc which will turn the water acidic.

I am assuming your tap water is relatively soft, which your apisto's should love. Unless your pH drops rediculously low (<5), then I would leave well alone. Most Apisto's will thrive in soft acid water.

Cheers

Brett

[parkap]

Thanks Brett, all great info. Didn't know tanins were acidic. Will test the water as you suggested as well.

Cheers,

p.

[steph]

Hi Parkup

Tannins are acidic, basically its tannic acid . Lots of Apsito's come from "blackwater" rivers where the water is actually dark brown from the amount of leached tannins from vegetation.

If you have lots of plants are you injecting CO2?? This will also make the water much more acidic, and maybe ? the plants are giving off enough CO2 during the night to make the water more acid. CO2 and water = carbonic acid. IF you are testing at the start of the day it might read quite acidic.

Just rereading your post you are saying the pH falls after doing a water change, so whats the pH before water change and what is it after ? Obvioulsy adding the water is diluting something enough to cause the pH to drop. You could try 10% water change more frequently which may see a more stable pH rather than a large amount.

Also be careful about raising pH to high to suddenly, at low pH ammonia become ammonium which is not toxic to fish, but if the pH is raised it turns back to ammonia resulting in an ammonia spike.

Cheers

Steph

[parkap]

Wow, thanks Steph. All new stuff I didn't realise. Although the testing of the water before AND after a water change is a basic thing I should've thought of myself.

Yes I am injecting CO2 although not on a regular basis at the moment as I'm having problems with the CO2 system. At the moment it's kind of 4 days on 2 weeks off... Based on what you wrote above, this might also then explain the changes to the pH I've been getting.

p.

[G-1000]

From what I remember crushed coral is very good at buffering for alkaline pH (keeps it around 8 to 8.5 or so)

G

[Daniel]

Just to confirm what Steph and others have said, I have been doing some tests with my Ph controller/monitor on my 200 litre non CO2 plants tank and the ph reading in the morning before the lights go on is 6.85. Sure enough slowly throughout the day my ph is rising and it peaks at 7.15 at night when the lights go off.

[Brett4Perth]

Well, well ... never take anything for granted. When I asked if you were adding anything else to the tank, I wasn't expecting to hear CO2. This will certainly drop your pH, in fact you can determine the level of CO2 in your water if you know the kH and pH. Plenty of tables around to help with the calculations.

Now the question is "which of the many potential causes of acidity is the most significant"

Cheers

Brett

ps Please don't add carbonates (coral, limestone, bicarb, etc) your apisto's will not enjoy it.

[parkap]

ps Please don't add carbonates (coral, limestone, bicarb, etc) your apisto's will not enjoy it.

←

Thanks everyone.

I'll be doing more testing now since my CO2 system is down (again). But funny enough the day it went down, the pH rose back up to 7. So looks like it's the CO2 system that's causing the drop in pH. Can this be countered or is it unlikely to concern the apistos? (PS. I also have other community fish in the tank, glass cats, peppermint B/N, borneo suckers, butterfly fish, blue rams, upside down cats.)

Brett,

Is shell grit a carbonate?

p.

[Brett4Perth]

Hi Parkap,

Try this link

It is the most comprehensive discussion on DIY CO2 that I have found.

Look at the chart that compares pH, kH and CO2 levels. You can see that the more CO2 you add the lower the pH, If you know the kH, you can calculate the concentration of CO2 you must have to achieve that pH.

kH is also refered to as carbonate hardness because it essentially measures the amount of carbonates in the water, mostly bicarbinate at the pH levels found in aquariums.

Yes, shell grit is mainly calcium carbonate and will increase your carbonate hardness and consequently your pH. However, the increased "hardness" is not enjoyed by "soft water" fish, like your apisto's. Depending on the species they may tolerate increased hardness, but most are from very soft environments. Caccatoides are an example of an Apisto that will tolerate harder water.

Try and stabilise your CO2, this can be difficult with DIY, what sort of set-up are you using?

Cheers

Brett

[steph]

ps Please don't add carbonates (coral, limestone, bicarb, etc) your apisto's will not enjoy it.

←

Thanks everyone.

I'll be doing more testing now since my CO2 system is down (again). But funny enough the day it went down, the pH rose back up to 7. So looks like it's the CO2 system that's causing the drop in pH. Can this be countered or is it unlikely to concern the apistos? (PS. I also have other community fish in the tank, glass cats, peppermint B/N, borneo suckers, butterfly fish, blue rams, upside down cats.)

Brett,

Is shell grit a carbonate?

p.

←

In my experience and from what I have read, the Apisto's will love the water. They do seem to thrive in heavily planted tanks and I can tell you most of the south american fish you are keeping there will also be happy especially the Blue Rams.

To give you an idea collecting data on M. ramirezi from Linke & Staeck gave the water parameters at < 1 dH of total and carbonate hardness, pH of 5.1 and approximately 1 microsiemen of conductivity, water temp 28.5C

Apistos collected from "black water" rivers are often found in water that measures in the 4's for pH

Cheers

Steph

[parkap]

Brett,

I'm using a commercial CO2 injection unit (doesn't include a pH controller) - although am having problems with it as mentioned before. The graph you mentioned on that link was very interesting. The kH of my tap water is around 3, so looks like I can use a lot less CO2 and still get the desired pH. However, while that will control the pH what about the CO2 needs of the plants? If I lower the Co2 input due to the pH dropping, will that mean that potentially not enough CO2 is being put into the tank for the plants?

Brett and Steph, from what you've both aid anyway, looks like I might not need to worry about the low kH and pH anyway for the apistos. Am a bit worried about the rest of the community fish in there though - although the apistos are my priority.

Regards,

Peter.

[Brett4Perth]

CO2 of between 10 and 20 ppm, is about right for plants. As it says on the graph CO2 > 35 is potentially dangerous for your fish.

So, if your kH is 3, pH range of 6.5 - 7.0 is about perfect. If your pH is lower than this then you are adding too much CO2.

HTH

Brett

[parkap]

Thanks Brett.

I've now raised my kH to 5 using a Sera kH upper - just a small dose. My pH is still at the bottom of my test kits measured exposure, ie. 6. Using the data you referred me to and doing some more research myself, the CO2 content in my tank would appear to be dangerously high [for the fish].

I hadn't thought I was injecting too much CO2 previously as I'm using one of those permanent Sera CO2 tests and it's been showing that my CO2 level in the water is fine.

I've now halved the CO2 injection from 4 bubbles/second to 2. I'll see how the pH is tonight and might reduce that further to just 1 bubble/second.

Regards,

Peter.

[Th0mas]

Hi Peter,

According to the fish you've already got, it might be better to seperate the apisto from them. Especially the upsidedown cat, it requires different water parameters to the apisto and will not like soft acidic water that much (as well as it might snack on the apisto during night if it is big enough).

Depending the type of dwarf you're getting, you will require to let the pH and hardness drop. I had apistos in the past and some species thrive between pH 4.5 - 5.5.

It seems your concern for pH drop will not be an issue for apistos, however it is not the case for some of your existing fish (peppermint will be fine, they are tough and handles pH 4.5 without any issue, however ram may not like pH dropping down that far).

IMO, better decide on the type of fish to keep in the tank first (ensuring they are from the same region would help simplify water requirement). Mixing fish from different region with different requirements maybe more trouble than what's worth.

Cheers,

Thomas.