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Re: Denton water

Cheryl Hoffman wrote:
> Next, please let me clarify: The analysis of the water I posted is NOT that
> of MY tap water. It is from a nearby city, where I work. The water that comes
> out of MY tap in Oak Point is saline solution. So much sodium that I wonder
> whether anyone has studied the incidence of hypertension in my area. :-)  A
> couple of years ago, when I posted the analysis of my OAK POINT water, I
> distinctly remember Roger Miller telling me I might have a problem with the
> high sodium levels preventing calcium uptake. James Purchase (where IS he, by
> the way?) said it was the worst water he'd ever seen. I think he was also the
> one who said Yuck. :-)

I stand by my original opinion.  The vast majority of public water
supplies provide water that is fine for growing aquatic plants; Oak
Point is in the tiny minority.  As I recall, you had pretty much no
measurable hardness, and sodium of 280 mg/l or so.  You couldn't even
mix that stuff with RO and get something useful.

The analysis you provided for Denton's water looks fine to me. (Hmm. 
Denton... Did you ever see "Shock Treatment?")
> So I am thinking of importing Denton water to Oak Point for the purpose of
> weekly water changes. That's why I posted the Denton water analysis to see
> what y'all thought of it.
> Here is some more information, for those of you still reading...
> I have Gomberg CO2 systems on both tanks (10-gallon and 30-gallon). Medium
> fish load.
> Nitrate 10ppm
> pH 6.9 - 7.0
> Phosphates 1-2ppm, sometimes higher. Why? Dunno.

See my comment below.

> GH 5-6 degrees
> KH 4-5 degrees
> PMDD, dosing KNO3 and K2SO4 separately.
> Iron levels right now are at about 1-2ppm. I have fertilized very little in
> the past few weeks because the levels just aren't dropping. I also have Jobes
> Sticks for Palms & Ferns in the substrate, which is half Fluorite and half
> gravel.
> 25% - 30% water changes every week.

And the ultimate test..  How are the plants growing?
> The medium-heavily planted 30-gallon tank has green water that even the
> diatom filter won't remove without a flocculant. There is 80 watts of light
> over this tank, on 9 hours per day. I suspect high light levels are causing
> the green water, but if set the CO2 any higher I kill fish.

I use more light than that on most of my tanks, both by watts/gallon and
light duration.  I don't think that's a problem.

> This has happened
> twice. The plants are not using the CO2 fast enough. Why? Something is
> missing....

I hope that your PMDD mix provides a balanced dose of trace nutrients. 
If it doesn't, then there are a number of trace element shortages that
you might never see in a tap-water fed tank that can come up in an
RO-fed tank.  A trace shortage could slow growth and allow other
nutrients to build up.

Assuming for a moment that trace element shortages *aren't* the problem,
your next most likely problem could be one or more bad test kits.  In
particular, I wonder about the phosphorus test kit.

For years I used a Red Sea phosphorus kit because it was the only kit I
could find locally.  It consistently pegged the scale at 3 ppm of
phosphate.  I tried a couple things to knock that level down and nothing
worked.  Then I found in my technical reading that phosphate is actually
a tough analysis and that there are significant interferences that can
cause false positives.

At some point I tried a new fertilizer (Hagen PlantGro) on a couple of
my tanks and I saw a big improvement in conditions.  The only unusual
ingredient in the fertilizer was *phosphorus*.  I even did some
semi-controlled dosing on one tank to test the plants' response. I
concluded that the phosphorus test kit was crap (the other dairy
product) and that my tanks were probably phosphorus-limited all along.

I threw the test kit away and stopped worrying about phosphorus.

You might try using a phosphorus-removing medium in your filter.  Test
the phosphorus in your water before adding the phosphorus remover, and
again after treating.  The phosphorus in your water should be gone after
the treatment.  If it isn't, then suspect your kit.
Concerning the green water, what's your filtration?  I had repeated
seasonal green water blooms in one of my unfiltered tanks.  I put
continuous mechanical filration (filter floss in a Magnum 350) on that
tank last fall and I haven't seen green water since.

I'm still an advocate of unfiltered tanks, but I lost "points" in the
AGA contest for cloudy water, and that colored my opinion.  I finally
concluded that for a show tank it didn't make much sense to wait 24
hours after disturbing the tank for the water to clear, so I started
filtering.  My other tanks are still unfiltered.

> The heavily-planted 10-gallon tank has some BGA, and too little light at 15
> watts, on 12 hours per day. I have another fixture on order but am having
> customer service problems with getting my merchandise. I suspect the high
> phosphate levels in this tank are causing the BGA. But with plenty of
> nitrates, the plants should be sucking those phosphates up. Why aren't they?
> What's missing? I have used erythromycin a couple of times, but it always
> comes back.

I'm increasingly convinced that we don't understand controls on plant
and algae growth.  The shortfall is partly because of inadequate test
kits, partly because we don't have a good handle on the energy budget in
our tanks and partly because we know almost nothing about either the
organic chemisty or the microbiology of the aquarium.

Based on my experience and on the things we *don't* know, I think
there's some general methods we can use to help prevent mystery

 * Provide light that is more than adequate for the plants you grow.
 * Avoid RO water if possible; use a more chemically complete tap water.
 * Watch plants carefully and try to avoid prolonged nutrient shortages.
 * Don't treat a tank with any kind of poison -- antibiotic or other.
Gee.  From all the extra blithering you'd think I had some extra time on
my hands...

Roger Miller