Tap Water and PH

[TCLynx]

I want to make sure everyone knows that the pH of your tap water immediately after you draw it from the pipes, may not be real pH of your tap water.

This is some info that I didn't originally know it is caused me all sorts of confusion. Water from the pipes or well is often depleted of O2 and full of CO2 the carbon dioxide in the water forms a weak acid which will give a lower pH to the water if measured right away. If you take that same water and let it air (run it through a system or put it in a bucket with a bubbler) to let the CO2 escape then test the pH again, the pH will often be much higher. Example, my well water comes out of the tap with a pH of about 7 usually and after outgasing, it will have a pH of about 8.

This is important to know when doing water changes in a system that is likely to settle with a much lower pH or if dealing with a system that is not fully cycled and you are having high ammonia since higher pH makes ammonia more dangerous to your fish.

It is also good to know this info about tap water when dealing with pH balancing issues. If you are trying to hold a pH around 7 and adding lots of tap water causes pH to go up, then you want to keep water changes and additions small so the system can bring the pH into line without lots of bouncing.

[Kate Mink]

I've found that a SMALL quantity of vinegar from time to time lowers the pH in my system (raft; tilapia) and doesn't bother fish or plants at all. I've let it all run at 7.4 to 7.6, used the vinegar when it pushed up to 8, may start trying to run it lower.


Jeff Givan said:

Thanks for your help TC. We live out in the desert in So. California. All of our water is either pumped from a giant underground aquifer, but most of it comes from what they call the American Canal, which is basically the Colorado River. Most of these canals are lined with concrete. And, the water from the aquifer is also very high in ph. So, I am doomed with high ph. I just tested this morning after a long period of not testing and the spagnum peat moss is working. It is down around 7.5. I learned this trick from the old days of raising an Amazonian fish in aquariums. The only drawback is that it makes the water a little brown. When doing it in the aquarium I put a biofilter on the back of the tank and instead of having media I would just keep stuffing the peat moss in there, but it has to be spagnum. Back then it was long and stringy, now days it is ground up so I have to put it in fine material so it doesn't make a mess in the pond. I also have in the house a 135 gallon aquarium and I have the opposite problem with that. My ph in there runs between 6.5 and 7.0 and I use the same water. The difference is that in the aquarium I have 2 huge pieces of drift wood that help soften the water. The rocks in the bottom of the pond are river rock of the granite persuasion. I do have red sandstone in the waterfall that only runs about 2 hours a day. I know that is not helping, but not hurting a lot. I will change that in time.

TCLynx said:

Oyster shells are a calcium carbonate type buffer that will keep pH from dropping too low. Basically they tend to help keep pH above 7.6. They DO NOT lower pH.

FYI, I have attempted to lower pH in a system that is really strongly buffered to 7.6, it doesn't work. You might lower the pH temporarily but as long as some of the buffer remains, it will dissolve some more and raise the pH back up.

Jeff, do you have any rocks or concrete or plaster or anything that might affect the pH in your pond? I expect that if you were to aerate your tap water in a bucket for a day and then test the pH again, you will find that the tap water has a pH even closer to 9. What is your source water, well water?

A heavily loaded bio-filter can compete a bit with high pH media but only to an extent. I've seen my AP system get down as low as 7 when there was a heavy load of fish and the feed rate was high but now that the temps are cooler, the pH is back up.

[Lon Wells]

In Washington State it is required that a business has a MSDS sheet for every product that is on the premises, and that those MSDS sheets are available for every employee to view. It is a wise practice and it make me look for healthier product to use.

RupertofOZ said:

Emma Lysyk said:

A friend suggested an additive called Blackwater. Would this contain buffer, or do I need to get a more concentrated version?

Emma, firstly let me ensure you that I realise that you run ornamental fish... as opposed to most in aquaponics that stock freshwater fish for eventual human consumption...

And to assure you that nothing personal is intended in any way...

And to declare quite clearly my almost universal to all aquaria based products... as most on other forums would no doubt be aware...

Why.... quite simply because most are poisonous and or carcenogenic... and extremely hazardous to human health...

To be specific about the "Blackwater" product you mention...

Firstly... No ... it does not contain any pH buffering agents what so ever...

Secondly, after a little research... frankly I think the manufacturer should be sued for complete mis-representation and mis-labelling....

The product description reads...

Blackwater Extract contains trace elements, vitamins and extract of peat. It replicates blackwater conditions by creating clear, “natural”, Amazon-biotope conditions in the aquarium. Blackwater Extract promotes fish activity levels and is an excellent conditioner for all soft-water fish including discus, angelfish, tetras and killifish.

http://www.tetra-fish.com/sites/tetrafish/catalog/productdetail.asp...

But once I found the MSDS... I found that the product actually contains NONE of these things... or at least NONE of them are the "principal" ingredients...

The "principle ingredient" is in fact a Class 1 poison... banned, or heavily restricted in aquaculture... with known human side affects and issues of "sensitisation".... which I wont bother to reference at this stage...unless people wish to know...

The principle ingredient is often used in aquaculture.. for disease control, principally for treatment of severe finrot and parasites like "ICH"... perhaps their justification for "happy, smiley fish"...

The MSDS... http://whatsinproducts.com/msds.php?brandId=7988&PHPSESSID=754a...

Clearly states the principle ingredient .... as Formaldehyde ... "Formalin" ...

And frankly, compared to the Australian MSDS for Formaldehyde/Formalin... is soooo understated and benign... as to be concerning...

For those that want to persue it further... try googling "formalin"... or "toxic affects of formalin".. etc, etc...

It is extremely scary stuff... albeit that this product might be susbstantially diluted...

In standard form... inhalation, particularly in asthmatics... can cause respitory collapse... and full, almost hazmat style suits are recommended... at least here in OZ...

IMO... other than perhaps for those stocking ornamentals... dont use it... in fact IMO... don't use any aquaria products in aquaponic systems which contain fish you intend to eat...

[Robin]

this is useful, thanks!