Tropical Fish Keeping - Aquarium fish care and resources

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BigBlue 01-11-2007 04:19 PM

Water Chemistry query - natural water source
Hi, I'm new to the forum - have posted a long message in the saltwater forum - first mistake. My question is for a freshwater tank. I have a water supply direct from the hills (Scottish Highlands)ph of 6 .5 as measured by lfs with a digital monitor. When this water is placed in a bucket and aerated for 48 hours the pH increases to pH 7.0 (the latter reading via a master test kit, not absolutely accurate but definate colour change). I have read that this is caused by 'gassing out'. Can someone please advise what this means. At the moment I only have 2 fish in a rescue tank of 21 ltrs, but my new tank of 180 ltrs which is being cycled will need bigger water changes. Is the solution to areate every time to get rid of whatever is raising the pH, as this will be problematic for me. This is my second attempt at cycling the 180 ltr tank, as the pH climbed to 7.8 from a pH of 6.5. I have changed the substrate, which appears to have affected the water (viniger test) to a totally inert one and added several plants with Laterite plant food in granuler form. I realise that the pH might swing until the cycle is complete, but for the small tank, I am concerned that the pH will need to be matched, although I would prefer to maintain a pH of 6.5 and increase KH only where needed for the fish I wish to keep. There is no KH reading from the hillside water, which is to be expected, so buffer capacity is non existent at the moment. If I add up to 4 degrees of KH to the small tank in stages, will this 'fix' the pH to the undesired level? I would then need to keep adjusting the pH to this new level, currently around 7.6 to 7.8, which I do not want. Can you help.
Many thanks, Maria, (BigBlue).

Lupin 01-11-2007 09:09 PM

Hi and welcome aboard.:wave:

It seems most of the places in Scotland have very soft water..Edinburgh, Glasgow, etc... The reason why you have increasing pH level when the water is aerated is that the oxygen level was also increased. Surface agitation dissipates CO2 and therefore increases oxygen level. CO2 lowers the pH whereas oxygen increases pH. pH isn't an issue unless you have pH swings brought by use of pH chemicals wherein the pH returns to its 'usual' level after the chemical's effects have worn off. Another thing is use of CO2 injection with a KH lower than 3. This will cause the CO2 to drop by all of a sudden killing the fish. This phenomenon is pH shock.

Increasing KH will allow the pH to stabilize.:) Be careful not to add the KH too much as it will then be difficult to lower the pH to the desired level.

BigBlue 01-15-2007 05:57 PM

Increased pH with aerated water - safe lowering of pH?
Thanks Blue for info, will take on board.

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