ph spikes

[gypsy3]

hi all....can anyone explain to me why i keep getting high ph spikes? i do 50% water changes every 3-4 days. the aged water has added hcl to bring the ph level down to about 6 -6.2.did a water change 2 days ago and checked the ph today as some of the fish were looking a bit dark,and it was up past 7.8. i used some ph down to reduce it, but i believe this stuff is not all that reliable. is that true? today i checked the fresh water i age out of the tap and it was around the 6.0 mark, thats before adding hcl. all other water parameters, ammonia ,nitrates etc are fine.

[Robdog]

It could be other things in your tank that are pushing the ph around. Substrate, decorations like certain rocks etc all have the ability to raise your ph value.
What else do you have in your tank?

[ILLUSN]

there is something in your tank or filter leaching carbonate into your water.

[gypsy3]

the only things in the tank are driftwood and plants, 2mm gravel base. so do i keep adding ph down on a regular basis if it continues to fluctuate, or is that not a good idea. i really cant think of any reason for the spikes.

[ILLUSN]

whats the gravel made of? take some out let it dry and put a few drops of HCl onto it, if it bubbles and fizzes you'll have to remove all of it.

[Xtreme]

Hi there,

Do u have a kh testkit?
if so do a quick test and see what its at
Im not too sure on the water up there atm but down here not a lot of people have much of a kh reading in their tanks and this might be the
culprit for ur ph swings

Just a thought

[Merrilyn]

I think you'll find the gravel is the problem.

Take some out and put it in a clean container. Fill the container with clean tap water and let it stand for 48 hours, then test the water again. If the pH has gone up again, you'll know for certain it's the gravel and you'll need to replace it.

[gypsy3]

thanks for the replies. will do the gravel test and see what transpires

[Greggy]

I might be 100% wrong in relation to your actual pH swings but I thought I'd share my experiences and point(s) of view...

Is your tap water hard or soft? Hard tap water can test as neutral out of the tap as I know mine does as from the tap it measures about 7.0-7.2 but when I leave it for a few days in a clean plastic bowl it reads anywhere up to 7.6 to 7.8 !

Water companies do their best to dissipate any disolved CO2 in the water they supply to your house because tap water with a lowish pH causes corrosion issues in copper pipes etc. If your tap water has a pH of 6.0 straight from the tap try putting some in a clean plastic softdrink/soda bottle and shake it vigorously for a minute or so then test it again. If the reading is at all higher perhaps your tap water has some dissolved CO2 in it.

For me its like this...

Water..........................pH
Direct from tap............7.0-7.2
A few days later..........7.6-7.8
In the tank no CO2.....7.6-7.8 (no CO2)
In the tank with CO2...7.2 (with home made CO2 injection 2x 2L yeast fermenters and 1x home made powered CO2 injector)

I see the above pH changes occuring probably because hard water tends to 'buffer' the pH so that it naturally wants to climb up a bit. In my opinion this is actually a good thing, because buffered water is generall more pH stable than soft water, thus its more forgiving to mistakes that us fish keepers tend to make from time to time.

Adding pH down products (such as Sodium BiPhosphate powder etc) is generally a waste of time when used with hard water as they just create pH swings of their own and can increase algae issues due to excess phosphates in the water. They don't hold the pH down for long as the dissolved carbonates in the hard (buffered) water tend to use up the available H+ ions and the pH again climbs back to its original levels.

Regards,

Greggy

[gypsy3]

thanks for the reply greggy.thing is tho, why would the ph go up dramatically when the aged water( about 48 hrs with hcl added to bring it down), go up after a day or 2 when its added to the tank? anyway, i've done about 80%water change today, added aged water with low ph ,put some gravel aside as suggested by merrilyn....i'll see what happens in the next few days

[ozarowana]

How long after adding the HCl do you measure the pH?

[Greggy]

I'm not saying your gravel isn't your problem, but you might have hard tap water as well which will mask/complicate the problem and its resolution.

I used the very same gravel in my 6x2x2 as I did in my Mum & Dad's 3x18x18. My pH (without CO2) is 7.6-7.8 whilst they have 6.6-6.8 (which suits their Angel fish and Tetras just fine).

The difference?

I have hard tap water, they have soft!

Regards,

Greggy

[gypsy3]

hi...ozarowana, imeasure the ph when i add it and also just before i pump the water into the tank, usually aged for 48 hrs. greggy, yeah its really strange. i tested my ph straight out of the tap yesterday, it was fine about 6.2. i tested some again today out of the tap, it was way out there, about 7.6. dunno whats going on.both times i tested the water twice, just to make sure reading was right.

[ozarowana]

I assume you are using a digital meter? I would agree that you should try and get a hardness reading to see what you are dealing with. Maybe a tap, aging barrel and a tank reading after a few days.

[gypsy3]

no, i just use a normal ph test kit, however it seems to be pretty reliable. will pick up a kh kit tomorrow. can someone please give me a quick rundown on kh and what it means?

[ILLUSN]

kh is the buffering capacity of your water, it is also call alkalinity, it it a measure of disolved carbonate and bicarbonate. a high kh is usually associated with alkaline water.
Real discus are acidic soft water fish and prefer a kh of below 5, however domestic discus are proably alot more flexable.

[WAZ]

KH or Carbonate Hardness is a measurement of both Carbonate and Bicarbonates present in the water.

The problems we are facing now is due to the condition of our water supply coming from our taps (in Sydney).

The main concern is the Kh levels in our current water supply - I have been testing water quality all over the Sydney Region for the past 6 months and I am getting readings of 0dH to 0.5dH everywhere. The best reading I have had was 1.0dH.

Very Important : A minimum KH of 4dKH is required to lock in the pH.

So...........if we do a water change with the new water showing minimal readings of KH levels, it is going to effect your pH dramatically.
Yes we can adjust with either pH up or pH down (or whatever) to achieve our required ph levels............but test it the next morning and it will have returned to where it was before you wasted the effort (and money) using the buffer.

It is now CRITICAL that we test for KH levels and as said they must be at a minimum level of 4dKH to stabilise the pH.

Talk to Xtreme Aquariums (forum sponsor) they have a new product called KH Powder 7.0 which will raise your KH by approximately 4dKH and stabilise PH to around neutral and lock it in till your next water change.

HTH
WAZ.

[gypsy3]

thanks for that...makes things a lot clearer

[ILLUSN]

You also need to remember that adding HCL to a tank reduces the KH. the reaction goes

H+(from HCl) + HCO3-(disolved bicarbonate) --> H2CO3(unstable carbonic acid) --> H2O + CO2.

[gypsy3]

ok, now you have me confused again illusn. if adding hcl to your aged water is a good thing ( to bring down ph) but it reduces your kh, and buffers have no effect, or are of little or no use, then what is the answer to keeping the kh at an acceptable level?

[ILLUSN]

what is the answer to keeping the kh at an acceptable level

With super soft water like i have in sydney you dont!
Add a tablespoon of crushed coral to your filter, this will leach CO3- at a slow rate and stop a ph crash (you proably wont ever measure a kh reading but your ph wont crash to below 4 (my breeding tanks are at 4.8-5 anyway).

your probLem is the reverse, just quietly i think your kH will be fine if not a little high, i'm guessing that sometng in your tank is bringing up your ph or that you have hard water with a high kh and gh, in which case the only answer is an ro unit.

years ago in my old tank i stupidly used crushed coral as a substrate an could never get my ph below 8, no mater how much ph4 rain water (0kh 0gh) i put in.