PH low

[Fiori]

I have 4 tanks, 2 x6.5 galls (UK), 1 x 5 gall and one 40 gall currently going through a fishless cycle. Although my tap ph is 6.8 to 7, the tanks' ph always drop to 6, which is the lowest reading on my test kit ( liquid tests). I am assuming it is the bogwood in each tank and the fact that we have soft water here, although I've never actually tested for the exact reading.

My new cycling tank will eventually house fish that like soft, acidic water and the plants I have chosen like the same. The mollies, platies and plec I have so far in the other tanks are thriving and the PH is always stable.

I did a 25% water change on the big cycling tank, just to check on how easy it would be etc and noticed that even with that amount being changed, the tap water addition did not affect the PH, which still stayed at 6.

I suppose the question I am asking is if this may cause any problems in the future when the tanks are mature. Having read threads on old tank syndrome and resulting ph crashes etc I am a bit concerned as my PH is pretty low already. Should I be trying to raise it a bit now or just leave it as it is naturally?

Sorry for the longwinded essay.

 

[CFC]

Before you start to worry about your pH you need to test to see what your KH (carbonate hardness) is. If you have a moderate KH then your water will have a good buffering capability which means the pH cannot change easily provided basic routine maintainance is carried out on the tank. If your KH is low then you may have possible future problems with the pH dropping below 6 unless you add a artificial buffer to the tank in the form of baking soda or a calcium rich substrate. Other factors such the ammount of bogwood used, whether you use peat filtration and if you use CO2 injection for plants will also factor highly in how safe and stable your pH may be.

 

[Fiori]

Thanks CFC - I will need to go get a test kit and check the KH

 

[Fiori]

Wellll - here goes.

My kh in tap water is less than 1 dh - the colour changed on first drop! My GH is about 1.5. I got another ph test kit which reads at lower levels and it was reading 5 from the tanks, as low as the test will go. Basically my fish are swimming around in a vat of acid (tho strangely it does'nt seem to bother them)

So my water is so soft and has no buffering capability at all by the looks of it. Yikes!!

I have added some coral sand for the moment to try and raise the kh. I spoke to my lfs and they told me they have to do this to all their tanks as the local water is so soft. Hopefully this will raise the ph a wee bit as well. I've also stopped using the co2 in the big, fishless tank for the moment - with those readings its not suitable for fish, even without the additional co2.

Any other suggestions welcome pleeeese!!

 

[slimecoat]

Wellll - here goes.

My kh in tap water is less than 1 dh - the colour changed on first drop! My GH is about 1.5. I got another ph test kit which reads at lower levels and it was reading 5 from the tanks, as low as the test will go. Basically my fish are swimming around in a vat of acid (tho strangely it does'nt seem to bother them)

So my water is so soft and has no buffering capability at all by the looks of it. Yikes!!

I have added some coral sand for the moment to try and raise the kh. I spoke to my lfs and they told me they have to do this to all their tanks as the local water is so soft. Hopefully this will raise the ph a wee bit as well. I've also stopped using the co2 in the big, fishless tank for the moment - with those readings its not suitable for fish, even without the additional co2.

Any other suggestions welcome pleeeese!!

Your water problems are similar to mine. Mine is dH of 4 as it comes out of the tap, so not quite so bad, but still not much buffering capacity. My pH was 7.3, so I added Bullseye 6.5 and that brought it down to 6.6. I also added some coral to the filter, and after 2 days the dH is now 8. Of course the Bullseye is supposed to add some buffering as well.

Unfortunately the pH has crept back up to 7.1 (will the coral tend to increase alkalinity at the same time as increase dH?)- anyway, so I added a supplementary dose of Bullseye. It'll be interesting to see what I have tomorrow.

 

[Def]

Fiori, with a kh that low you will need a huge amount of coral to buffer it (and you'll have to keep replacing it too). I have exactly the same problem as you. To solve it, I add half a level teaspoon of bicarbonate of soda to every 10 litres of fresh water while doing a water change. It's taken a long time (months), but I've managed to raise my kh up to 10 without affecting PH. The important thing to remember is to *take your time*. Do NOT dump bicarb straight into the tank, and do NOT dose more than half a teaspoon per 10 litres into the fresh water before you add it to the tank. If you don't do this, you will screw with the ph in the tank and potentially cause your fish damage through ph shock.

 

[Fiori]

Thanks for all the advice people - I'm lucky in that the big tank is currently undergoing a fishless cycle, so it is my smaller tanks with the fish - who actually all seem fine anyway. They must be acclimatised.

I was concerned about any new fish I get for the larger tank, when the cycle is complete, but that may take yonks if my ph is so low, cos the bacteria will not grow properly *sigh*. And I'm trying for a planted tank this time as well.


My lfs man said that bicarb was only a temp solution and recommended the coral sand - I have to say it looks crap on my sand substrate tho Just as well that I only added half , to monitor any changes.

Blimey, this hobby is hard work!!

 

[slimecoat]

and do NOT dose more than half a teaspoon per 10 litres into the fresh water before you add it to the tank. If you don't do this, you will screw with the ph in the tank and potentially cause your fish damage through ph shock.

So that's how it works. By taking it slowly the pH doesn't rise?

 

[Def]

slimecoat, precisely. If you dump a load of bicarb the ph will go through the roof. I'm sure that adding small amounts like I said also affects the PH, but doing it this way has raised my kh from 2 to 10 and kept my ph at 7.6 (which is what it comes out the tap at). Slow and steady, patience.

My lfs man said that bicarb was only a temp solution and recommended the coral sand

Well I guess it is, but only through our own actions. Because you're adding bicarb to the water, then removing & diluting it through water changes, you have to keep buffering the fresh water. Coral sits in the tank and buffers regardless of water changes because you're not removing it. But, 2 problems. First, it looks crap and you need a lot of it. Second, coral does eventually use up its buffering capacity and your KH will begin to drop. So you'll have to take out all the existing coral and put in fresh. Big pain.

 

[Fiori]

I think I won't put anymore coral sand it - damn and blast for the stuff in there aready! Bicarb sounds the best bet I think - cheers for the help Def.

 

[steelhealr]

Hi Fiori....I have similar problems. My pH would slowly slide to mid six range. I got a gH/kH kit and after testing, I'd have out of the tap a gH of 2 and kH of 2. I tried adjusting with bicarb over two days. One reference said a tsp of NaBicarb per 50 gallons. My kH went up to 3 but my pH did rise a little to 7.0 from a usual 6.8 after a water change. Some of my fish..in fact a lot of them...prefer soft slightly acidic water so this concerns me. Adding the coral or limestone may do it slowly, but, since it contains calcium, it may bring up your gH. If you pH is that unstable, I would think you need to improve the kH. Def made the rec to me as well and went with his advice. Even tho' my pH rose, it did stabilize it. SH

 

[Fiori]

A small ph rise would be good anyway; although the fish I am planning for the big tank like soft, slightly acidic water, a ph of 5 is perhaps a bit on the low side

I'm hoping to get this sorted before there are any fish in the tank, so thanks to everyone for their input.

 

[slimecoat]

Hi Fiori....I have similar problems. My pH would slowly slide to mid six range. I got a gH/kH kit and after testing, I'd have out of the tap a gH of 2 and kH of 2. I tried adjusting with bicarb over two days. One reference said a tsp of NaBicarb per 50 gallons. My kH went up to 3 but my pH did rise a little to 7.0 from a usual 6.8 after a water change. Some of my fish..in fact a lot of them...prefer soft slightly acidic water so this concerns me. Adding the coral or limestone may do it slowly, but, since it contains calcium, it may bring up your gH. If you pH is that unstable, I would think you need to improve the kH.

Just trying to understand the chemistry here. The following is part of an explanation I found on the web.

Water Hardness:
The degree of water hardness relates to the amount of dissolved minerals, especially calcium and magnesium, in the water. Water hardness is generally expressed in the amount of calcium carbonate (CaCO3). Water hardness is measured in ppm (part per million), kH (carbonate hardness), and dH (degrees of hardness) or gH (general hardness). Water is expressed as soft (having few dissolved minerals) or “hard” (having many dissolved minerals. General levels of water hardness are expressed in the table below (1 dH is equivalent to about 17 ppm).

very soft 0 to 70 ppm 0 to 4 GH (dH)
soft 70 to 135 ppm 4 to 8 GH (dH)
medium hard 135 to 200 ppm 8 to 12 GH(dH)
hard 200 to 350 ppm 12 to 20 GH (dH)
very hard over 350 ppm over 20 GH (dH)

For most aquariasts water hardness is not particularly important. However, excessively soft water can cause problems. Because softer water has less buffering capacity due to a lack of CaCO3 (a natural buffer), and is subject to pH crashes, where the pH falls dramatically causing harm to aquarium inhabitants.

Carbonate Hardness: Carbonate hardness (kH) is not used as a measurement of hardness as often. KH includes the presence of minerals and charged ions, other than Ca and Mg, dissolved in water.
[EndQuote]



So, wouldn't it be GH not kH that indicates the water had buffering capacity to avoid unstable pH ?

 

[Fiori]

I found this on the web - might help clarify a bit:

*Quote*

GH (General hardness) measures the cations (+ charged) of calcium and magnesium in water

KH (Carbonate hardness) refers only to the bicarbonate and carbonate anions (- charged). It is a confusing term, as it does refer to hardness - but with relation to the alkalinity produced from the carbonates and bicarbonates.

Alkalinity is is the ability of a solution to resist a pH change with the addition of an acid. Other anions e.g. hydroxide, borates, phosphates and silicates can affect the alkalinity, but it is the bicarbonate/carbonate buffering which provides most of the alkalinity in aquariums.

KH and GH are usually close to each other but can vary, depending on the cations and anions in the sample. For example:

NaHCo3 (Calcium Bicarbonate, I think) added would raise KH and not affect GH.
MgSO4 (Magnesium Sulphate) would raise the GH and not KH.

Increasing carbonates will either raise the pH or need counterbalancing CO2 added to maintain the pH level.

*End Quote*

 

[steelhealr]

Hi...from basic chemistry, acids are usually proton (hydrogen ion) donors, bases are 'acceptors. BiCarbonate, HC03 -, accepts hydrogen ions and therefore is a base. A buffer helps resist changes in pH by either absorbing or donating a hydrogen ion. CaCarbonate, when dissolved, provides the carbonate anion which can accept 2 hydrogen ions. So....if you have a high kH, ie, buffering capacity, and your tank tends towards acidity, the carbonate ion will pick up the acid (hydrogen ion) and convert to C02 and H20. pH will be stable until all buffering capacitiy is used up.Hence, stabilizing your tank from rapid pH swings.gH measurements reflect the amount of cation in the water, or Calcium and magnesium. Hope this helps (sheesh...my chem prof would be proud). SH