The pH of rainwater..... there goes another theory...

Unless there is something wrong with my digital pHmeter...... I've just eliminated another theory I had about rainwater.....Icannot say where I heard it, but I've always been of the opinion that purerainwater weighs in at just above 6.5 (or less)....

Well... we've had rain all day (so far) and I've got drumsbelow every downpipe and must've collected about 4,000 litres already. I justmeasured the pH in one of the drums and it comes in at 7.6......

Can anyone please confirm to me that that is possible.....

And then also...... How do I apply 4,000 litres of purerainwater to justify my efforts to collect it.....

 

Hi Cheetah,

Its not so simple.

What sort of a pH meter do you have, I mean is it a pen type meter or a laboratory pH meter with a separate electrode.

Second point: the pH of soft water such as rainwater will drop as CO2 dissolves in it and this will take at least a day or two, so at this stage the pH has not stabilized yet.

Then what is your roof and your gutters made of?

And what are the containers that you have collected the water in, is this a water tank and how long has it been in use.

If you can answer these questions I can give you an explanation.

Kind regards,

Dirk

 

Hah!.... I;m slowly regaining my confidence in my original theory.... My post above was done about 2 days ago before I posted it here..... As you said...... The pH had not stabilized yet. In order to answer all of your questions..... I went outside again and remeasured the Ph...... This is the current stance, (and also shows the digital pH meter I'm using....



The rest of your questions are answered in the following photographs.....

1. The receptical I'm using is this plastic drum whic was previously used as sump for one of my ponds, but has been standing empty (after a thourough wash) and upside down for at least 8 months....



This is a top down view into the drum..... the water looks almost cycled:


And finally..... this is the roof and gutter structure... it has been raining 60mm for at least 3 days on end so it should be flushed and I may add.... I live close to a platinum mine which is not productive atm due to the Christmas break......

 

Ok, the container you collected the water in is ok, it is made of polyethylene and particularly if you have used it before it is OK.

You pH meter LOOKS ok, but you should realize that the cheaper the pH meter, the cheaper the electrode and cheaper electrodes don't give an accurate measurement in soft water. Rain water is soft water and therefore this pH meter may not be giving you an accurate reading. However, it does measure a slightly lower pH which indicates that it is moving in the right direction because there is no doubt that CO2 will dissolve and cause the pH to drop. If you have distilled water it would drop to pH 4 overnight.

Now your roof: AN UTTER DISASTER!!!!!!!!! This is therefore galvanized iron and which is steel that has been coated with zinc. This oxidizes so that it does not have the bright shiny colour of new galvanized iron sheets, but the zinc oxide will leach into the runoff water at low levels constantly. YOU CANNOT KEEP SENSITIVE FISHES IN THIS WATER, that is the bottom line.

Oh, and finally, do you see that little creature sitting under you tv aerial (the dak kakker), he carries Salmonella bacteria and you don't want them in your aquarium either.

Sorry Cheetah, either get a new tiled roof or you can use this water in your garden only, but not in your fishtanks please.

Kind regards,

Dirk

 

Thanks for your time & response...... My wife has this theory about washing your hair in rain water...... Hmmmm!!.....??

 

Show your wife the duif on your dak and then ask here about washing her hair in that water.......

It would be ok for washing in though.... but not for making eish.

Kind regards,

Dirk

 

Ha! Ha!...... I got one quick reply...... Pigeon shit makes your hair grow...... scientifically proven she says!...... (lol)

 

Mmmm, the wives always have all the answers, and we know that we cannot argue with that!!!

 

Hi @Dirk Bellstedt

If you dont mind me adding a bit just for interest sake.
We also had stacks of rain in PTA in the recent week and I collected some for my Discus. I always do but leave it for a few days before I use it. During this time I filter the rain water through activated charcoal and aerate it heavily using an airstone. After about two days I tested the water and got the following results.
Ph 5.4 -5.8
TDS 6ppm

This was collected from a tiled roof. I obviously do not use this water only as the ph will just keep falling. I have one question though. With a TDS that low, what are the chances of there still being "unwanted and dangerous" contaminents in the water, and that they are the ones showing up as the 6ppm dissolved solids in the water.
I have never had a problem using this, but there is always a chance I suppose. How much safer does it make the water when still filtering it through A/C

Thanks Prof Dirk

Rgds

Marco

 

Hi Marco,

In actual fact, the lower the TDS of water is, the easier it will be for that water to dissolve even trace amounts of heavy metals and other toxins. Water that is harder, and say has a high level of ions that have two positive charges such as Calcium and Magnesium, will be far less toxic if it additionally contains say 1 mg / litre of Zinc, than if your water contained no Calcium and Magnesium but did contain the same amount of 1 mg / litre of Zinc. In this instance, it is actually the Calcium and Magnesium which competes with the Zn very effectively and does not let it bind to parts of the cells of fishes where it can do the damage, instead harmless Calcium and Magnesium will bind there. However, without the Calcium and Magnesium, the Zinc can bind and then cause the damage it is known for. All this therefore has to do with relative amounts and competition to binding sites. Hope I have not made my explanation too complicated. Please ask more if you don't understand.

Kind regards,

Dirk

 

Hi @Dirk Bellstedt

Thank you Prof. Dirk. I think I do understand. Correct me where I am wrong please- due to the fish wanting to maintain a higher level of internal mineral content than what the water has (so water 'inside' fish has higher tds than tank water) they will be absorbing any and all dissolved minerals/toxins in the water to achieve this. I take it magnesium/calcium is much easier to absorb, but in their absence the fish will absorb whatever else there is, in your explanation Zinc, and then this will harm the fish. If however the water was harder the Zinc, more difficult to absorb would fall behind other dissolved, and easier absorbed minerals.

This then would explain nicely why some fish medicines say on the packaging 'Not for use with soft water fishes' or am I wrong? I would reason that in Soft water again too much of the chemical would be absorbed as there is no competition from other, more easily absorbed minerals.

Am I on the right track Prof.

Regards

Marco

 

Hi Prof. Dirk

Just a quick add on. A Gentleman I often chat to in Canada, Dale Jordan once succesfully spawned both Blue faced Heckel as well as Willi's Heckel in quick succession. He was however at the time revamping the plumbing in his house and replacing the pipes with copper piping. At 6 weeks the Heckel fry all mysteriously started dying. Within a week they were all dead. He had sent a juvie for an autopsy to some canadian university with the result 'copper poisoning'. Now, would I be correct in assuming, after the above discussion, that this was probably partly due to the soft water Heckel would require, and that had it maybe been domestic discus, which would probably have been growing in harder water, then there would have been a chance of them surviving as again, the copper would not have been as easily absorbed. It should be added that if memory doesnt fail me, Dale got very soft and acidic water from tap back then, meaning he would not have filtered that water at all

Thank you

Regards

Marco

 

Hi Marco,

You are partly on the right track, but there are a few more aspects. The ability of say Zinc, to be absorbed from soft water is greater, than in the presence of a lot of Calcium and Magnesium, but it also has to do with the toxicity of say Zinc. Calcium, Magnesium and Zinc are all charged ions (atoms) which have two positive charges. What this means is that they can bind to something that has two negative charges. Normally, inside the fish, there is a lot of Calcium and Magnesium and a tiny amount of Zinc only. Now you put the fish into the soft water containing only Zinc and it absorbs the Zinc via the mechanism that it would absorb Calcium and Magnesium as well, but now, inside the body, the Zinc binds to places that Calcium and Magnesium normally bind to. BUT although the Zinc can bind, IT CANNOT DO THE SAME THING as the Calcium and Magnesium do, in other words, some or other important biological function. So all of a sudden this function does not work any more, and this is therefore why we call the Zinc toxic, it actually stops a normal function which can result in the death of the fish.

In the case of the medicines both absorption and blocking of functions applies, and they are therefore toxic under these circumstances.

Kind regards,

Dirk

 

Hi Marco,

To answer your second question, discus are highly sensitive to copper and I have had bad experiences with this as well. When I started keeping discus which was in Stellenbosch in 1988 we had very soft and also acid water coming from the tap. My fish room had a copper pipe which lead the tap water into the room, but before it went into the room, it ran along a wall outside and the bare pipe was exposed to the sun in the afternoon. Well, my discus would breed and the young would go freeswimming but would die every time at about 6 days old. We were completely puzzled. I then brought along a copper test kit from Germany and we tested the water that had been standing in the pipe and the copper levels were excessively high and we were doing water changes with this. After this we would just let the tap first flush away the hot water from the tap before adding it to the discus aquaria and all of a sudden all the fry were surviving.

What is important is that copper is soluble in ACID water, not in alkaline water. Most municipalities now adjust the pH of tap water to about 7.5 to 8 specifically to overcome corrosion to concrete pipes but very specifically also to stop corrosion and solubility of copper, because such copper levels are actually also toxic to humans in the long run. Even though discus prefer acidic water, I am actually very glad that my tapwater is alkaline because I then know that I do not need to worry about copper toxicity.

So, yes, I think Dale is quite right, he must have had acid water in his system and therefore high copper levels which resulted in the death of all his fry. Also, when you have new pipes they are not coated with a layer of copper oxide yet and the copper goes into the water even more easily. Also, harder water containing Calcium and Magnesium would to some extent block the effects of the copper.

All makes sense to me!

Kind regards,

Dirk

 

I'm glad Marco is asking all these relevant questions and I'm learning a lot thanks Proff...... just another 2 things whilst we are on the topic.....

1) would the characteristics of a drum full of hail be much different than ordinary rain water once it melts........ (we had a semi hail storm last night and my drums are still in position)
2) I also have a smaller drum collecting water directly from my aircon drip off...... Can this water be used to advantage of the aquarist......

I am asking because I'm looking for an alternative source of water than the tap water, which currently measures around 8.2 to 8.6.......

 

on the topic of PH

Hi Dirk

I wil be starting up with Discus again shortly after a long dry period due to retrenchmentand. I am currently cycling my tank and conditioning my water with Prime, please can you tell me if seachem buffer will stabilise my PH and keep it stable at 6.8 or will it be ok to leave it at 7.4 (Tap water PH in Durban)?

Regards
Geoffrey

 

Hi Geoffrey.

I would not add anything to Durban water, it is soft and the pH will drop naturally in a short space of time. A pH of 7.4 is also not a problem for discus at all. I would like to give you some advice about discus and that is that there is an incredible marketing drive to sell you all sorts of stuff that you do not really need for discus but from which the shops want to make a huge amount of money, so be very careful with this. You have a very knowledgable discus keeper and breeder in Durban, Gavin McCann and I would contact him for fishes and also for food (can send you his cell number by PM, if you would like).

Kind regards,

Dirk

 

Hi.

@Dirk Bellstedt

Thank you very much Prof. Dirk. I understand that nicely now. Thanks for taking the time to explain it.
If more questions about this pop into my mind I hope you dont mind me putting them here.

@Cheetah

Apologies if I took over your thread here. Hope that as its still sort of relevant you dont mind.

Kind regards

Marco

 

lol...... as I mention in post #15 here...... it is relevant and I'm learning....... I just think that DiscussGeoff has stolen centre stage and diverted attentions from my (final) punchline questions....(lol)....- but also interesting, nevertheless - I honestly thought its a waste of time trying Discus above 6.8....... But if Proff Bellstedt will be so kind to revisit post no.15, I'll appreciate very much - thanks..... (seriously no offence Geoff...... with 2 posts I understand)......

 

Well Cheetah,

You really do seem to be touchy about the DiscussGeoff comments, what went wrong......?

The reason why I did not reply to your questions is because they are not clear. Did you collect a drum full of hail or did you let the hail fall on the roof and then collected the run-off? If you collected hail directly, then the water is ok, if you collected it off the roof, there is no difference to rain water.

The water condensing in an aircon, condenses onto bare metal and again you have the potential of metal toxicity as condensation water is also very soft. Bottom line is that this is not going to work either.

Please keep the questions on topic please folks, if you have other questions open a separate thread.

Kind regards,

Dirk