ph spikes

[gypsy3]

hi all....i've asked this question before, but it's driving me nuts and thought someone might have some further input. iage my water, add hcl to bring ph down to about 6, do 50% w/c twice a week. 2 days after doing a water change, the ph is back up to about 7.8 - 8.0, which is what the water out of the tap tests at. Have tested the gravel in a bucket of water over a few days, ph stays at about 6, which is what my aged water is, so it's not the gravel. Why does it go up so quickly in my tank?

Rather than messing around trying to bring it down, am i better off just leaving it at the higher ph and letting the fish cope with it? I'm concerned that the constant fluctuations might affect them more than the higher ph. The wilds in the tank don't seem to mind the high ph, at least i don't think so, they haven't shown any signs of illness or weakness. Anyone have any idea?

[ILLUSN]

If your still having problems then just leave it.

set aside a bucket of aged water (ph adjusted to 6) leave it for a couple of days and test it, its still at 6 something in your tank (or your filter media) is bringing it up, if its at 8 then its just your water and you'll need an ro kit if you want softer more acidic water.

[gypsy3]

ok, thanks for that...yeah, the aged water stays at 6 - the last lot has been ageing for 3 days and i tested it first day and today. buggered if i know what's causing it, as i also have had about 500 grams of eheim peat sitting in the tank.The gravel tested fine, the media is all eheim stuff - substrat and noodles, so that shouldn't be a problem.by the way, how high can ph get, and does it matter to the fish as long as its consistent?

[ILLUSN]

pH can get up to 10, in some african tanks.

soft water fish eveolved in soft acidic water, their enzymes are specialised to work within a certain range, Tank bread fish are tough but i wouldn't go above 7.8-8.0.

my second discus tank used a crushed coral sand that buffered the ph at around that level , it worked fine, but the fish never spawned and one day when i added a new fish i lost the entire tank to plague, used metro but with the high ph and some ammonia (from uneaten food rotting in the substrate) the fish never had a chance.

Something in your tank is causing the ph rise, i'd try to find what it is, just for pice of mind.

if you tank ph is 8 and you add ph of 6 the excess carbonate will bring the ph back up to 8 within a few days.

[the german]

ph of 10 :shock: almost at the point where you cant stick your fingers in there :lol:

[gypsy3]

mate, i've been trying....that's what's driving me nuts! I saved my guts out to get some wilds and i don't want to lose them, let alone the others.I'm just at a complete loss, there's nothing i can think of as far as what else it could be.Tank is planted, media is quality eheim, gravel has been tested and is fine...what else is there?

[ILLUSN]

I'm stumped, is there anything else in the tank, rocks or ornaments?

[gypsy3]

nope, nothing else except driftwood and i don't think that would be the cause

[ILLUSN]

sent you a PM mate

[FNQ]

Do you use zeolite? It can raise pH in really soft water. I have the same problem in Cairns. The water out of my tap has a KH of less than 10ppm and bounces like crazy.

[gypsy3]

nope...don't use anything.Illusn kindly did some testing for me and thinks it may be my gravel, but then it tests fine and stays stable when i test it in a bucket over a few days.I think i'll just have to live with a ph around 7.6 - and hope my fish do the same - so far so good.

[ILLUSN]

mate your gravel tested fine, the brown rocks in it are acid soluble but they took 5 days in conc HCl to disolve (limestone rich rock disolves in under 5 seconds at that concentration), the rest the white and yellow appear to be silica based and completely unreactive (proably diffrent types of quartz).

Pm me your address and I'll send the treated samples back to you so you can see which ones contained carbonate (in very low ammounts), might be just enough at a huge quanity to keep your ph buffered, but i'm thinking your water might be a little hard.

[ozarowana]

if you tank ph is 8 and you add ph of 6 the excess carbonate will bring the ph back up to 8 within a few days.

I'm also thinking along these lines. How big is the tank? How much water do you change in one go? How many times have you done this? Whats the kH of the tap water?

[ILLUSN]

the aged water stays at 6 - the last lot has been ageing for 3 days and i tested it first day and today.

if aged ph adjusted water in a bucket stays stable for several days, then the kH in the tap water shouldn't be causing the swings, its something in the tank that keeps "leaching" or "seeping" CO3-.

just a pity the gravel wasn't more reactive or else we'd have a definate answer.

[ozarowana]

But if the tank has a large enough volume and only a small amount of water has been changed there may be enough "residual" buffering to bounce it back up, hence the questions.

If it's not that, take all the substrate out and see if it changes things.

[gypsy3]

thanks for the advice, but changeing the substrate isn't really an option. its a heavily planted tank, quite a few fish and to be honest,logistically would be a real pain in the **** to do. Illusn, thanks for putting in the work, i really appreciate it, don't worry about sending the sample, i really don't think that's the problem. Based on advice given, and having watched the fish closely, i think i'll just have to put up with it, they seem to handle it ok.i'm going to give it one more test -fill a spare bare tank i have, bring it down with HCL and see what the ph stays at. Thanks for your input guys - appreciate it.

[FNQ]

ozarowana is right in what he's saying. if your tap water is really soft, it might be climbing to match the ph in the rest of your tank water.
Try adding some epsom salts to the new water once you have adjusted it.

Our water is <10ppm gh and <10ppm kh. When new water is added to the tank it's ph climbs until it matches the old tank water.

Adding epsom salts to raise the gh of the new water causes my tank ph to go back down to near the new water's ph rather than the tanks old ph.

Adding bicarb soda to raise the kh brings the ph up really high straight away, so steer clear of that and leave kh alone.