Ottawa Water Chemistry (from City of Ottawa)

[dpatte]

I have a meeting today with a chemist at the City of Ottawa water purification plant to discuss Ottawa water chemisty, ph, chlorine and chloramine and any other water chemistry-related topics.

I will be taking notes and will present a report at an upcoming meeting of the Aquarium Club.

:idea: If anyone has any water chemistry questions at all, please post them here, or phone me at 864-4240 before 2:00PM today (Monday), and I will try to ask the chemist whle visiting the filtration plant today.

[artw]

I would like a detailed content analysis that we can bring to the next meeting.... there is one online but it's from like 2002.

[saltydog]

David

Thanks for the invitation & this opportunity!

Question #1:
I purchased an RO/DI (Reverse Osmosis/De-ionixing) water filter to use to prepare water for a large reef tank which I will be setting up shortly. The company that manufactures this 3-stage filter informed me that chloramine in the water would quickly "use up" the active ingredient in the DI portion of the filter & I have found this to be the case.

Would anyone at the water purification plant know how chloramine might be removed from the water BEFORE it enters this filter. I have a an older type of water filter under my kitchen counter (NSA brand) which uses metallic silver as the active ingredient & effectively removes the chlorine taste from water. Might this work?

Perhaps one can store the water & gas off the chloramine by means of an air-stone. Does this work? The only difficulty of this method in my case is that I would have to repressurize the water afterwards as the RO/DI filter must have about 70 psi to function efficiently.

Question #2:
When is the best season, weather conditions, time of day, etc. to draw water for our tanks? Those of us with storage barrels could especially benefit from this knowledge. Even those without still have some latitude as to when he or she might perform small or large water changes.

Thanks again & enjoy the tour.

Roger

[dpatte]

This week I visited the city of Ottawa water purification plant and flooded ( pun :roll: ) the manager, Ian Douglas, with fish water questions.

First, to answer Arts request - yes I got the latest water chemistry tables - as a printout. They havn't published it internally yet so they where hesitant to give me a digital copy only a printout.

Here is a breakdown of the important components of the water chemistry for 2003 as an average when it hits the water distributioin system...

pH 9.2 (this decreases after drawing from tap, due to CO2 in the air)

All the rest are in PPM (parts per million)

General Hardness 33.9 (< 1.9 degrees hardness - tell your friends on the web and they will weep!)

Chloramine at plant:
1.2 winter
2.0 summer
(about 1/3 what US cities use)
Chloramine at tap is average .5 PPM throught Ottawa

Ammonia Nitrogen 0.08
Nitrite 0.17
Nitrate 0.03
(nitrite and nitrate or negligible but increase slightly during hot weather)

P = Phosphates & Phosphorus - 0.002 (VERY LOW)

K = Potassium - 0.77

Calcium 8.0
Iron <0.09
Zinc <0.1

watch iron and phosphates in your planted tanks and use water changes to restore trace minerals.

[dpatte]

Now to answer saltydog's questions:

1) there are many ways to remove chloramine.

Sodium Thiosulphate (ye old 'aquarium water conditioner') is the most effective, but other things are also used including

- sulfur dioxide (used in 'stink bombs'
- sodium bisufite
- sodium metabisulfite (used in winemaking)
- sodium suphite
- calcium thiosulphate

The key point here is that the sulphur from these chemicals reacts with the chloramine. The reaction causes some SO2 (sulfur dioxide) to escape in to their air, except for the calcium one. The ammonia remains in the water and conributes to the nitrogen cycle.

The amount of ammonia is about 0.5 PPM after the process.

The problem with ALL THESE is that they also eat the oxygen from the water if too many chemicals are used!!! The same for 'aquarium water conditioner' . Use too much and it can deplete the oxygen from your tank at the same time!!!

Activated carbon can remove chloramine from water as well. A brita filter (which contains only activated carbon) can remove up to 40% of the chloramine in the water. Activated carbon in your aquarium filter will remove up to 40% of the chloramine in your water until it is depleted after a few months.

Some tap water filters also contain silver, but that does nothing but prevent bacteria from growing in the carbon itself. Silver, and any heavy metals can be toxic to bacteria, but also humans and fish in larger quantities so be caustious if your filter contains alot of silver.


2) The best time of day, weather, season to draw water....

The plant output is extremely stable and they see no measurable difference in the quality of water over any of these type of conditions.

[dpatte]

oh, two other things....

1) if you are adding tapwater to your tanks, add the water conditioner first. water conditioner is far less toxic than chloramine.

2) i went with a fellow called Jean Legault. Jean has found a source for chlorine test kits. Where was that again Jean?

[artw]

Choramine at plant:
1.2 winter
2.0 summer
(about 1/3 what US cities use)
chromine at tap is average .5 PPM throught Ottawa

I assume those 2 typos above are supposed to be "chloramine"

chromine is something completely different, right?

thanks David. Would you mind doing a 10 minute at the next General Meeting?

[dpatte]

yes, sorry, i meant Chloramine

i have now edited the original post.

I'll see what I can prepare for a 10 minute lecture for next meeting

[Anubias]

Hi Dave,

I'm going to take issue with the suggestion that the water supply is basicaly stable. The City has made some changes over the last three years. I have a printout of the year 2000 Water Quality parameters. If the pH is now 9.2 it averaged 8.4 then. At my tap it has been as low as 7.0. About a year ago there were areas in the City where zinc poisoning was thought be a problem due to the low pH.

In 2000 the ppm calcium averaged 17.7 ppm out of Lemieux and Britannia. Now you say that it is 8. GH averaged 58 ppm as CaCo3. Did you say that it is now 32?

I've also noticed seasonal changes in the KH of my tap water. On occasion I've noticed abrupt pH drops. I've lost fish as a result. The City Lab never seems to want to release recent up to date Drinking Water Quality data. However, you can always get data one or two years old.

Concerning chloramine levels -they have been fiddling with these as well. Originally, the level was set just below 1.0 ppm year round. I was assured several times that the 1 ppm was accurate. This was more than adequate supposedly. I set the amount of sodium thiosulfate that I add to the tapwater based on their assurances. Now you say that the target at exit from the Plant is 1.2 to 2.0.
This explains a few deaths that I have had the last year subsequent to water changes.

In March 1992 we did a tour of the Britannia Treatment Plant and were told that there would be no switch to chloramine in the near future. The guide was very pleasant. Five months later the switchover was complete. The rational was cost saving and a substantial reduction of trihalomethanes. Later I was told that the saving was $5000 per year, a drop in the bucket. The switch from chlorine to chloramine has cost millions over the years to a lot of different interest groups including ourselves.

My suggestion would be to add the exact amount of conditionner recommended on the bottle. With chloramine one is supposed to add twice the amount of sodium thiosulfate suggested for chlorine.

Towns in places like Texas with very dirty water add the most chloramine to the effluent, 2.5 to 3.0 ppm. Walkerton must have done a real number on these civil servants.

Glad you had a nice tour.

[artw]

I disagree with the point you make regarding doubling the amount of conditioner required to "break the chloramine bond".   If you need 1 drop per gallon to remove chlorine from regular chlorinated water,  you should need the same (exactly 1 drop) to remove the chlorine from chloramine.   the chlorine will bond with the sodium as soon as it sees the sodium ions.  Chemically I don't understand why you would need twice the amount of sodium (thiosulphate) to cause this reaction to occur. (specifically the separation of chlorine and ammonia)

[Anubias]

There have been some papers written on the subject. They are probably still available on the WEB somewhere. Unfortunately, I lost  the two files about a year ago in an operating system switchover (along with the other 2000 fish files of note). The amount of sodium thiosulfate required also increases substantially as pH increases if I recall correctly. The paper also offered chemical equations for anyone interested in calculating the exact amount of sodium thiosulfate required, given the temperature, pH, and chloramine levels in the sample.

Regards,