question about ph

[joephys]

I'm beginning to wonder if I'm in the wrong business and should have become a chemist this stuff is really interesting

A chemist is someone who wasn't smart enough to become a physicist. :joke:

I think it would be best to not use water from the softener for your tank if possible. Its unnatural for fish to have that much disolved material with their water without any calcium or magnesium.

 

[LunchBox]

I was wondering about that. I don't know what all the softener deos to the water, but I have to think that it takes away somethings that would normally be ther eas well as adding some salinity. not sure if this will point anything specific out about it but last night I tested my kh and it was at 11, which doesn't seem dangerous, just a little on the higher side. I was wondering if maybe that had something to do with the softener.

I'm going to see if my faucet in the basement is ahead of the softener and perhps start taking my water from there.

 

[RTR]

Most household water "softeners" are sodium-exchange resins. Calcium and magnesium ion make water "hard" (literally, it is hard to produce a foam with soaps). Sodium chloride recharges the resin, trading two Na+ ions for each Ca++ or Mg++ ion (the exchange must charge balance or the water would be electrically charged - which won't happen). The resulting water is better suited to laundry, but in TDS, Total Dissolved Solids, it is higher (more minerals) than it was before the device due to the two-for-one requirement. IMHO, water softener output is not well suited to fish tanks. The pre-softener water is likely to be better. "Softened" water is not going to kill the fish, it can be used, but the presoftener water would be better.

 

[Roan Art]

Many relatively soft water area utilities use short-lived phosphate buffers (yes, the same stuff sold for "buffering" tanks) to keep the water alkaline and thus protect the copper pipes. This water tends to come out of the tap at least mid-7s if not higher, then drop to low 7s or below after a day or two or three.

Hrm hrm, this is sounding too familar. Northern VA, pH 7.4 in winter, 7.8 in summer, phosphates 2.0ppm.

You utility can be your friend - in this country they are required by EPA to inform their clients - but you do need a bit of background or Googling to catch on to what it all means directly on the hobby tanks. The county next closer to DC from us (Montgomery) uses Potomac water (as does DC and parts of NVA), so must add buffers to avoid pinhole leaks in the residences there. Aged water from such systems drops in pH rather than going up. Pressurized surface water does not carry the CO2 load of deep-well water in this area.

Ack! Could have sworn the test put my tap water higher and not lower. I *do* know that when I aerated off the CO2 in my tank overnight last week, it was up to 8.0. BUT I'm pretty sure the phosphates were also down to 1.0. Hrm, I thought that phosphate had to be in excess of 5ppm for it to affect the pH? Did I read that wrong?

I'm going to test again. Should I aerate the sample?

Roan

 

[RTR]

In a tank the level of phosphate to affect the pH depends on the form of phosphate first and most (there are many - very complex compounds are common), then on the KH of the base water, finally on the quantity and the accuracy and sensitivity of the test. Many hobby kits only measure part of the range of phosphates added to or present in water supplies.

Low KH waters will low organic loads can be buffered up briefly by small amounts of phosphate buffers. When that water is put into high-organic fish tanks, the phosphates get gobbled up by bacteria, algae, or just organic acids and may vanish from view quickly. Remember, to a lymnologist or water chemistry person, all of our tanks are eutrophic.

 

[Roan Art]

In a tank the level of phosphate to affect the pH depends on the form of phosphate first and most (there are many - very complex compounds are common), then on the KH of the base water, finally on the quantity and the accuracy and sensitivity of the test. Many hobby kits only measure part of the range of phosphates added to or present in water supplies.

Ah, thus the crux of the common belief of the inaccuracy of the test kits. I see that now. So my tap water is most likely higher in phosphates than my kit reads. Haven't done the aged tap water test yet.

Low KH waters will low organic loads can be buffered up briefly by small amounts of phosphate buffers. When that water is put into high-organic fish tanks, the phosphates get gobbled up by bacteria, algae, or just organic acids and may vanish from view quickly. Remember, to a lymnologist or water chemistry person, all of our tanks are eutrophic.

Interesting. So most likely in the case where my low 2 dKH (out of the tap) tank went up to 8.0pH, with a phosphate level of 1.0, the "undetectable" phosphates were gobbled up leaving behind that which does not buffer the pH? Would that be correct? If so, then my tank consumes far more phosphates than I assumed. If true, then using any type of phosphate remover in a situation such as this would prove detrimental?

What exactly do plants use phosphates for? Or do they? I mean, they will consume it so long as nitrates are available, but what do they utilize it for?

Hope I got all that right

Cool, learned two new words today, too!

limnologist: the scientific study of bodies of freshwater
eutrophic: the process by which a body of water becomes enriched in dissolved nutrients (as phosphates) that stimulate the growth of aquatic plant life usually resulting in the depletion of dissolved oxygen

Definitions from Meriam-Webster.com

Roan

 

[RTR]

NPK are commonly called the macronutrients, as plants neeed and use more of them than the other mineral nutrients, the micronutrients and/or trace elements. Submerse plants generally require less P than emerse plants, something like ~7+ parts N to 1 part P. Planted tank folk tend to work at about 10:1::N, largely because it is not critical and the math is simpler. They also work at N=K approximately.

Phosphate is the great energy element - ATP* and its ilk are the energy mediators in both plants and animals. I have forgotten the relative percentages in dry plant mass for aquatics, but if you are in phosphate lack, everything from photosynthesis to growth stops. Producing energy storage compounds? Phosphate compunds are absolutely required. Burning those componds? Phosphate is the mediator again.

This led to the great fallacy of phosphate-limitation to control algae, a theory which dominated planted tanks for a long time. Over-zealous P control arrested plant growth, which of course allowed algae to take up the slack. Many grower spent more time testing than maintaining their tanks. Many were saved more by the inadequacy of the tests than by the validity of the theory. But I am sure it helped Hach and LaMotte's business but ever their tests are good to very good field grade, which is well short of lab grade.

Phosphate levels are not tightly critical in planted tanks so long as there is enough to be non-limiting, and not far above 3ppm in other than the highest light/CO2 fastest growth tanks.

*http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/ATP.html

None of the nutrient lists commonly include C (carbon, specifically bioavailable carbon), which is just over 40% of plant's dry mass, because it comes free in the air - for terrestrials. Unfortunately it is not free for tanks other than low-light slow-growth setups.

 

[Roan Art]

NPK are commonly called the macronutrients, as plants neeed and use more of them than the other mineral nutrients, the micronutrients and/or trace elements. Submerse plants generally require less P than emerse plants, something like ~7+ parts N to 1 part P. Planted tank folk tend to work at about 10:1::N, largely because it is not critical and the math is simpler. They also work at N=K approximately.

That was rather a dumb question on my part. Asking about P, I mean. I knew it was a macro, but since I don't have to dose it, I always forget that it IS a macro and is required. Only time I look at it is when I'm trying to up my nitrates.

Phosphate is the great energy element - ATP* and its ilk are the energy mediators in both plants and animals. I have forgotten the relative percentages in dry plant mass for aquatics, but if you are in phosphate lack, everything from photosynthesis to growth stops. Producing energy storage compounds? Phosphate compunds are absolutely required. Burning those componds? Phosphate is the mediator again.

DOH! I know the answer to the next part without even looking now

This led to the great fallacy of phosphate-limitation to control algae, a theory which dominated planted tanks for a long time. Over-zealous P control arrested plant growth, which of course allowed algae to take up the slack. Many grower spent more time testing than maintaining their tanks. Many were saved more by the inadequacy of the tests than by the validity of the theory. But I am sure it helped Hach and LaMotte's business but ever their tests are good to very good field grade, which is well short of lab grade.

Wow. I just didn't realize how important P was to plants. Now I know why everyone told me to leave P alone and increase N instead.

Phosphate levels are not tightly critical in planted tanks so long as there is enough to be non-limiting, and not far above 3ppm in other than the highest light/CO2 fastest growth tanks.

I'm seriously doubting that I need my tanks at 3.2wpg high light plants or no.

*http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/ATP.html

None of the nutrient lists commonly include C (carbon, specifically bioavailable carbon), which is just over 40% of plant's dry mass, because it comes free in the air - for terrestrials. Unfortunately it is not free for tanks other than low-light slow-growth setups.

Huh. Gonna print that out and read it tonight.

Thanks, RTR
Roan