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Posted by smartbomb on April 17, 2005, 1:48 pm
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On thrid week of patiently waiting while my live rock, live sand, salt
water and bacteria cycle.
Ph is still 7.4-7.8 I was under the assumption that I should be using
distilled water to top off evaporated tank. Then someone told me
distilled had a ph of 5.
Any suggestions?
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Posted by Pszemol on April 17, 2005, 11:07 pm
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> Ph is still 7.4-7.8 I was under the assumption that I should be using
> distilled water to top off evaporated tank. Then someone told me
> distilled had a ph of 5.
pH of distilled water is not important in this case.
Low pH of distilled water is caused by small amount of CO2
dissolved in it. This effect is normal, due to the surface air access.
The same amount of CO2 will dissolve in your tank water,
but it will not cause pH drop due to buffers existing in the water.
Distilled water is lacking buffers so CO2 influences pH strongly.
Don't know what salt mix you use and how do you measure pH
but maybe you need more reef buffers in your water...
Check your alkalinity levels.
Also read this very informative article:
http://www.advancedaquarist.com/issues/june2002/chem.htm
Be carefull in playing with pH level - even relatively low pH level
like yours is better than large pH variations you might cause...
The bottom line is: adding distilled water will NOT drop your
pH level in the tank. Adding distilled (or purified in other ways,
i.e. RO/DI) water is the only way of properly replace evaporated
water and adjust salnity level to the normal level.
Feel free to ask if you need to know more.
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Posted by George on April 18, 2005, 1:43 am
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>> Ph is still 7.4-7.8 I was under the assumption that I should be using
>> distilled water to top off evaporated tank. Then someone told me
>> distilled had a ph of 5.
>
> pH of distilled water is not important in this case.
>
> Low pH of distilled water is caused by small amount of CO2
> dissolved in it. This effect is normal, due to the surface air access.
> The same amount of CO2 will dissolve in your tank water,
> but it will not cause pH drop due to buffers existing in the water.
> Distilled water is lacking buffers so CO2 influences pH strongly.
>
> Don't know what salt mix you use and how do you measure pH
> but maybe you need more reef buffers in your water...
> Check your alkalinity levels.
>
> Also read this very informative article:
> http://www.advancedaquarist.com/issues/june2002/chem.htm
> Be carefull in playing with pH level - even relatively low pH level
> like yours is better than large pH variations you might cause...
>
> The bottom line is: adding distilled water will NOT drop your
> pH level in the tank. Adding distilled (or purified in other ways,
> i.e. RO/DI) water is the only way of properly replace evaporated
> water and adjust salnity level to the normal level.
>
> Feel free to ask if you need to know more.
Hmmm. See my earlier post called "RO and pH issues.
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Posted by Pszemol on April 18, 2005, 9:58 am
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> Hmmm. See my earlier post called "RO and pH issues.
You do NOT need to add buffers to the top off RO water.
You do NOT need to add Calcium additives either.
Try not to reinvent the wheel - read more chemistry
articles and do this stuff the right way.
If 100% of marine tank keepers do not play with top-off
water, also, if the Nature just drops rain water without any
added buffering to the ocean - you do not need to process ro
water either... Acid pH level of RO water is not important!
If you leave it in the bucket for several hours any excess of
CO2 will escape the water (and other gases will equalize as well).
After several hours in the bucket the water will have NORMAL
level of CO2 and other gases (Nitrogen, Oxygen) dissolved in it.
So in terms of gases, what RO membrane stops or leaves behind there
is not important! http://en.wikipedia.org/wiki/Partial_pressure
If your tank water is unable to support high calcium
levels and the level is 280mg/l check the water parameters
to find out the reason why it is this way. There are several
good articles about keeping right calcium levels, check out
the website I gave the link to before...
Adding calcium to the ro water and then pouring this
water to the tank water might cause calcium precipitation
and covering everything with white snow... If your tank
water does not support high calcium levels you will not
force the water to high levels this way... sorry.
Do not experiment unless you are sure what you are doing
(i.e. have good background of basic chemistry courses).
Change your focus from your RO - your top off water or its pH is NOT
the problem here. Try to focus on your tank water parameters instead.
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Posted by George on April 18, 2005, 7:43 pm
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>> Hmmm. See my earlier post called "RO and pH issues.
>
> You do NOT need to add buffers to the top off RO water.
> You do NOT need to add Calcium additives either.
>
> Try not to reinvent the wheel - read more chemistry
> articles and do this stuff the right way.
I have two years of college chemistry, have a masters in Geology, and have
raised fish for most of my 46 years. What more chemistry do you think I need in
order to understand that if you add unbuffered water with a pH of 5.0, you are
going to dilute the buffers in the existing salt water, and will affect the pH,
especially since that make up water has a lot of CO2 in it with a pH of 5.0?
> If 100% of marine tank keepers do not play with top-off
> water, also, if the Nature just drops rain water without any
> added buffering to the ocean
The oceans are miles deep, so overall rainwater has little affect. However, the
topmost layer at the surface is in fact affected by rainwater.
> - you do not need to process ro
> water either... Acid pH level of RO water is not important!
If that is the case, you won't mind if I pour a bottle of HCL into your
aquarium, since pH is not important to you.
> If you leave it in the bucket for several hours any excess of
> CO2 will escape the water (and other gases will equalize as well).
This is incorrect. The RO water I tested for pH was in an unsealed five gallon
plastic container, and had been made at least four days before I tested it. The
pH was 5.0, indicating high concentrations of CO2 in the water. Once I add
buffers and aerated the water, the pH rose to 7.5.
> After several hours in the bucket the water will have NORMAL
> level of CO2 and other gases (Nitrogen, Oxygen) dissolved in it.
Wrong, wrong, wrong. Make up a gallon of RO water, test the pH, then leave the
water in an unsealed plastic container for four days, and then test the pH
again. Then come back and tell me that the pH has stabilized to an acceptable
reading (5.0, in my case, is not acceptable, and since the pH was at 5.0 after
four days, I can imagine what the pH level was at one day. I plan to find out
tonight).
> So in terms of gases, what RO membrane stops or leaves behind there
> is not important! http://en.wikipedia.org/wiki/Partial_pressure
See above.
> If your tank water is unable to support high calcium
> levels and the level is 280mg/l check the water parameters
> to find out the reason why it is this way.
I'm sure it is able to support higher calcium levels. The thing is that all
marine reef tanks use up calcium so it has to be added. I hadn't added any
calcium since my last partial water change (about a month). That is why the
calcium levels were low. I had been adding buffer periodically, however, which
is why I was suprised that my pH was only 7.5. I have a wave maker which causes
a lot of evaporation, so I have to add makeup water frequently. This is why I
am convinced that the unbuffered RO water was the culprit.
> There are several
> good articles about keeping right calcium levels, check out
> the website I gave the link to before...
> Adding calcium to the ro water and then pouring this
> water to the tank water might cause calcium precipitation
> and covering everything with white snow...
I only add enough clacium to the RO water to make it the same as my tap water,
which is 60 mg/L, not enough to cause precipitation since even at that level,
adding it to the tank water (which has a concentration of 280 mg/L) is still
diluting the tank water. After a couple of days, I will check the calcium
concentration in the tank water to see if addition calcium is needed.
> If your tank
> water does not support high calcium levels you will not
> force the water to high levels this way... sorry.
Why would my tank water not support high calcium levels? The only reason for
the levels to drop in the first place is because the animals and macroalgae in
the tanks are using it. That is why you have to add calcium periodically to
reef tanks. I have 4 inches of aragonite sea sand in the tank and three inches
of it in the refugium, so the pH isn't going to fall below about 7.5.
> Do not experiment unless you are sure what you are doing
> (i.e. have good background of basic chemistry courses).
See above. Ok Einstein, what is the vapor pressure of CO2? Note. I've had
reef tanks for 14 years (but have only used RO for the last two years), have a
maroon clown fish that is also 14 years old, have a 1,200 gallon garden pond,
and have raised tropical fish since I was 11 years old. I am also a geologist
(more specifically, a hydrogeologist).
> Change your focus from your RO - your top off water or its pH is NOT
> the problem here. Try to focus on your tank water parameters instead.
The other parameters are fine Temp = 78 F, Nitrate = 0, Nitrite = O, Ammonia =
0, hydrometer reading 1.023.
The problem is NOT the tank water. The problem IS the make up water. I never
had this problem when using an ion resin filter (DI). It was only after I
started using the RO filter that the problem occurred. Note: I took the RO
water that had a pH reading of 5.0 and added buffers and calcium to it, to bring
it up to a pH of 8.0 and a calcium concentration of 60 mg/L. I did this last
night. Today, I added this water (three gallons) slowly to the tank. The tank
water is now at 8.0 and the calcium reading is at 360, which is just below the
normal level for a tank after you've added fresh seawater to it. The pH is
still low, so I will change it over the course of the next few days.
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> distilled water to top off evaporated tank. Then someone told me
> distilled had a ph of 5.