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Hello,

I very much enjoyed Ned’s detailed suggestions for switching to a planted tank (last post 06/06/06). Thanks Ned. I have additional questions about the water issue.

MWRA aims for a pH of 9.1 with an alkalinity of 40 mg/L, and the GH of the supply is naturally <1 (MWRA claim 7 ppm at the source, 15-20 at the tap). To achieve this pH, they dose the supply with sodium carbonate. What they aim for is in fact precisely what I measure at the faucet in Somerville and I would expect that many, if not most people on this forum deal with the same water. The easiest way to lock the pH at 7 for a community tank is with phosphate buffers and for good reasons. The pKa’s of phosphoric acid are pKa1 = 2.1, pKa2 = 7.2 and pKa3 = 12.6, which are obviously ideal for a neutral buffer. However manufacturers do not recommend using phosphate buffers with plants. I assume that’s because the plants would soak it up, making the pH crash (or are phosphates toxic to aquatic plants above a certain threshold?).

Obviously a large number of people have been very successful at keeping planted tanks with MWRA tap water. I should add that I now only keep tetras and other soft water-loving fish in my 36 gallons tank, and would aim for a pH of 6.5.
What’s the most reliable way to achieve this?
- Can phosphate buffers actually be ok?
- CO2 injection seems like the most logical and preferred option. How does one maintain a fairly constant pH using CO2 injection starting from tap water with the aforementioned specs, taking into account 30% weekly water changes, etc? (as an aside, is peat of any help to stabilize the pH, since it releases organic acids, or do people simply use it to soften the water?). I understand that the pH goes up and down naturally in a planted tank, but it still has to be within reasons for the fish to be happy, right?
- Non-phosphate buffers? They amount to replacing CO2 with another source of acid (I believe the Seachem acid buffer is sodium bisulfate). Once the bisulfate is consumed, all that’s left is carbonate and CO2, and as CO2 is gradually desolvated and released into the atmosphere, the pH creeps back up. Which takes us back to CO2 injection… Continuous CO2 injection certainly beats having to add bisulfate every day, notwithstanding the accumulation of sulfates. Does anybody use Seachem acid buffer as an alternative to CO2? Why do they even sell the stuff? By nature it makes for an unstable system.

I would be grateful for your advice and other successful aquarists’ experience with plants and MWRA water.

Thanks very much in advance.

Jul

sodium carbonate, in my experience is extremely strong but extremely unstable...
so if there is not alot of calcium in the source water,
the water should drop back to whatever pH it wants to be at in a
short ammount of time...

in your case, if the water right out of your tap is 9
(too high really)
I would barrel it or bucket it
for at least an hour
before you put a lot of it in your tank,
particularly if your fish are used to being at 6.5...
7 - 8 is not too big a jump, but 6 - 9 is...
(if your only doing small water changes,
it is possible that no adjustments are necesary)

in the barrel or bucket
I would put a small ammount of
Aquarium Pharmeceuticals "pH Down"

then put in some
Aquarium Pharmeceuticals "Proper pH 6.5"
according to the directions

Aquarium Pharmeceuticals
is the brand I know best...
there are many products on the market that do the same thing

generally,
I let my fish get used to the local water...
(my cardinals do fine at pH 7.7 after they are used to it for a few weeks)

I feel it is more important that the fish get substantial regular water changes, than to be exactly at any particular pH.

the safe range for most fish we keep is 6.5 - 8.5
"if it can't live here, it doesn't live here"

KH (carbonate hardness) is more important to know
than GH (total dissolved solids)

water with high KH usually has high pH,
but not always

most plants require high kH to thrive
there is a geat plant list and their KH requirements
in Inez Shuermann's Book "Aquarium Plants Manual"
published by Barron's

it is possible to have an extreme low pH disaster
in tanks that are already somewhat low in pH
where you also add CO2
(usually with the lights off)

in general, running a low pH tank is trickier
than running a medium or high pH tank
(it is also not necesary to run pH low,
for all but the most selective of plants and fish,
stuff nobody buys anyway)

in my experience,
the proper PH 6.5 product will not let the pH go above
(and more importantly, not below pH 6.5)...
I have never tried it in a system with CO2 'tho

the short answer is
the less chemicals you fool around with,
the less you have to worry about

also...
if it ain't broke, don't fix it

phosphate

the reason most
planted aquarium hobbyists
try to avoid phosphate
is that phosphate feeds unwanted algaes

phosphate is added to many city's water systems (Medway)
it is also in the water of many wells (laundry detergent)
it is probably in many water supplements sold to aquarium hobbyists (not sure which, most these days claim "none")
it is certainly in fish food (made from fish meal, which is made from fish bones)
...however I'm not enough of a chemist to know it what form [compound] the bad algaes like it...few of my Medway customers have nuisance algae problems

I know this for sure, if you keep adding water to replace for evaporation,
and never take out any water..
you are adding more and more and more of whatever solids are dissolved in the water
(the only thing that comes out with evaportion is pure water vapor)

this is where you get the wierd aquarium chemistrys,
I once had someone come in
with water that had pH off the scale low, under 4
and GH off the scale high,
he hadn't done a water change in the tank for 9 years!!!
all the fish died of course

Believe me, I only settled for buffers because my pH 9, KH 2 water would settle at about 8.2 in the tank, which was just too high, and too many fish died, despite otherwise perfects stats, regular water change, etc. (great for my cichlid tank though).

The phosphates that come from fish food, water supply, etc amount to just a few ppm. Buffering the water with Aquarium Pharmaceuticals "Proper pH 6.5" results in hundreds of ppm of phosphates, quite a different proposition. Did you mean that you use "Proper pH 6.5" or any other phosphate buffers in planted tanks, with success? (or does anybody else uses them with success?)

if you are getting that strange of a result...
I would just cut the tap water with Reverse Osmosis water
or rain water
(or use straight RO water or rain water,
...then add back "RO Right"
or some other stabilizer)

I also don't think your fish were dying from having a pH of 8.2...
there are too many easier ways to kill fish

try a cheap experiment
fill a bucket with tap water
wait 2 days
don't do anything else
test pH and KH
in the bucket
see if it doesn't fall back to 7.2 pH on its own

It is possible that you have useless tapwater,
a few towns are AWFUL !,
it is more likely you are trying too hard

I have never used
"proper pH 6.5" in a tank with CO2
(sounds like a not good idea, too many variables)...
I do use it all the time
(and love it)
when we get wild imports from
Southeast Asia
or South America
in holding tanks with just a few plants

Thanks, Ned.

I guess I was hoping to avoid having to invest in a CO2 system, but that's what seems to make sense with regard to water chemistry and plant health.

With my KH of 2 and no phosphates, roughly 15 ppm of CO2 is what it takes to get a pH of 6.6, which is good for both plants and fish. It doesn't come cheap though, especially if one wants to automate the CO2 system with a pH controller. Sounds like fun though...

Why would you want something cheap?

Well, I guess I’ve been missing an interesting discussion. I think most of it has been said, but I thought I’d chime in. Ned is right about his little experiment being the first step. You should know what your water is going to do on its own before you decide how to further mediate the pH. He’s also right about the fact that fish readily adapt to a wide range of pH’s.

What I think got lost along the way is that the CO2 does double duty. Yes, it will solve the problem of a very high pH. But moreover, your plants need it to grow. Of course it all depends on the light level, type of plants and fish load of the particular tank. You could run a low light tank with crypts, anubias, java fern, mosses, etc. with all CO2 and nutrients being provided by the fish. However, if this is a planted tank with fast growing stem plants you’re going to want more. In this type of set-up, phosphate buffer is not a good idea. Your water has a low kH (40ppm/17.9 = 2.2dKH). You want to age your water to get a (true) starting pH (just for curiosity sake) then add sodium bicarbonate (baking soda) to raise the kH to about 4dkh (71ppm). Then add CO2 to bring the ph down between 6.5 and 6.7. I know that the various online calcs and plant sites recommend maxing out the C02 at 30ppm, but many folks (including myself) go above that with no obvious fish problems. You would also be surprised what fish can take as far as a swing. Now, I wouldn’t recommend that the ph swings all the time (too much throughout the day)… but a rise in pH once a week with your water change (tap water with no pH and bicarb added with have a significant effect) really isn’t a big deal.

As for peat, this isn’t the best idea if you are going to use CO2 because the way we monitor the gas concentration is by its effect on pH. If you have tannins in the system that are also bringing down the pH, the numbers won’t crunch right and it gets confusing.

Finally, a note about pH controllers: they are only as safe as the probe is accurate. If your probe is reading high, it will allow for much more co2 then is safe. If you have a controller, use it as a back-up not as an actual controllers. What I mean is, set the bubbles/second so that it just keeps up with gas exchange and plant use so that your pH is where you want it and the controller hardly ever turns off. If you push the gas flow up really high, and the controller has to turn off and on constantly, you run the risk that the controller thinks there’s less gas dissolved then there really is. I would recommend just a bubble counter and a solenoid on a timer. Let the CO2 run constantly from just before the lights come on until just before the lights go off. You will save gas, and depend less on the controllers accuracy. A good regulator, needle valve, solenoid, and bubble counter are all you really need, no controller.

That’s all I have for now… ask more questions, there’s quite a few knowledgeable folks on this board and we are happy to help. You seem to be comfortable with the chemistry, but ask if anything I wrote is unclear. My CO2 system is easily the best investment I made for my tank. Plus, one more toy to tinker with… so much about this hobby to enjoy.

Regards,
Abby

<You>

Quite perceptive there Abby, I do have a PhD in chemistry. Which does not mean that I want to fool around with water chemistry, just keep fish alive and maybe in the future keep some healthy plants. Anyway, these were some very helpful comments, and right to the point, thank you.

A few questions with regard to what you wrote:

- <I> How much above 30 ppm? Are some species more sensitive to high levels of CO2 than others (just thinking how much is made these days about losing species to rising ocean CO2 levels)? What's your favorite way of measuring CO2 concentrations?

- <but> That was a very interesting comment, but the meaning of the part you wrote in brackets got lost- scrambling, typos, not sure- Could you clarify this bit?

- Great comment about the controllers. I am still wondering how it's done practically. Do you tie yourself to your tank for the first few days, taking a zillion measurements/day/night, settle for a particular gas flow and then hope for the best. Or are you bound to a life of constant monitoring? Or am I making to much of this and the whole system is actually quite stable, despite plant growth, fish load change, etc (remember my tank is only a 36G)?

Ta. Jul

The unclear sentence that got lost in the previous post was:
"but a rise in pH once a week with your water change (tap water with no pH and bicarb added with have a significant effect) really isn’t a big deal."
Sorry about that.
Jul

Well, I only have anecdotal evidence about which fish are more sensitive to high CO2…. A while back I was running a very high light plant tank and was flirting with the high end of both CO2 and ferts. I had a rio powerhead seize up that was my only source of surface agitation and I lost 5 fish. I lost (all) three Steatocranus tinanti “Lionhead cichlids” and (all) two Siamese algae eaters. The remaining fish were fine… clown loaches, gouramis, and rasboras. I don’t know if the problem was the high CO2 or the low oxygen, but both of the fish I lost are “fast water” fish that require good oxygenation. Unfortunately, I don’t know just how much CO2 built up because I noticed the powerhead had seized up before I noticed the dead fish and I got it going again and that dissipated the CO2. I am generally more worried about a low pH than I am about the actual CO2 level. I run my CO2 in the 40-50ppm range (KH=4-5, pH 6.4-6.5). I do have a pH controller, which I maintain by calibrating at least every two weeks. Beyond that, I keep the bubbles per second such that the controller never, or hardly ever shuts off. I check regularly with a liquid test kit. I have tried expensive and cheap and I’m as happy with the aquarium pharmaceuticals kit as I am with any. To tell you the truth, once you get into it and get a sense for what is going on in your tank, you will be able to almost predict the CO2 levels by looking at the tank. I expect to see pearling from about 1-2 hours after the lights come on until a few hours before I turn the lights off. This varies of course, with your light and nutrient levels, but the take home point is that it’s possible get a sense of the C02 in the tank by looking at the plants and animals.

From a practical perspective, the CO2 can be worrisome to set up, but once you know what sort of bubbles/second you need you can almost “set it and forget it”. I would generally do a few tests the first weekend to know what I going on. In your case your KH is low and your pH is high. I would set aside a little time when you will be around the house…. Then turn on the CO2 at 1-3 bubbles per second and test a few times in the next couple hours… it doesn’t take very long for the co2 concentration to come up in the tank. Because you have a low KH the pH will drop quickly with little CO2. As the pH comes down, slowly add baking soda until the KH is where you want it. Then adjust the bubbles per second until the pH stays where you want it. This is all much easier with a pH monitor/controller/pen, but it’s certainly not nesscicary. To reiterate, these devices are very useful, they just shouldn’t be depended on. The amount of gas you need depends on the amount the plants take in, the amount of surface agitation, and the effienecy of how its dissolved in the tank… you could/should run it into the intake of a power head or canister filter so that it dissolves efficiently and you aren’t wasting the gas.

There are a lot of “methods” out there for keeping planted tanks. Depending on your interest level, I would recommend looking into the Estimative Index, developed by Tom Barr and the Perpetual Preservation System which is popular on Aquatic Plant Central. I like the EI method, because I feel more comfortable doing waterchanges than water tests. There are searchable forums that cover both methods.
http://www.barrreport.com/forums/showthread.php?t=1
http://www.aquaticplantcentral.com/foru ... ables.html

Hope that clears things up. You caught me on a few slow days at work ….

Abby

Great stuff. Thanks a lot.
Regards,

Jul