Sodium Bisulfite (pH Down) Throwing off Phosphate Tests

[Ekso]

Hey everyone,
Brand new user here! So first off, Hi! Now, on too business...

I recently went through a huge phosphate crisis (or so I thought) and had to go through a myriad of procedures to remove them. WELL, after doing a series of water changes AND using Tetra Phosphate-Minus, my phosphate tests were still off the charts. Knowing that there was no way the test was accurate I proceeded to do control tests on specific media.

I used a eye dropper to put 1 mL of each individual chemical I used in my tank with 9 mL of phosphate free RO water and ran phosphate tests on each one. Suprise, suprise, guess what one turned the water totally dark blue/black upon doing a phosphate test? PH DOWN was the culprit!

On the bright side, I now know that the active ingredient in almost every PH regulating product on the market ( sodium bisulfite ) turns modern phosphate tests into a useless bottle of blue dye. Downside is, how can I test my phosphates while at the same time regulating my pH? Has anyone had to navigate this issue before? If so, what was the solution?

Thanks for reading, and spread the word about Ph down messing up phosphate tests so no more poor schmucks like myself have to run the gauntlet of tests to figure out nothings wrong!

 

[dw1305]

Hi all,

I recently went through a huge phosphate crisis (or so I thought) and had to go through a myriad of procedures to remove them. WELL, after doing a series of water changes AND using Tetra Phosphate-Minus, my phosphate tests were still off the charts. Knowing that there was no way the test was accurate I proceeded to do control tests on specific media.

I used a eye dropper to put 1 mL of each individual chemical I used in my tank with 9 mL of phosphate free RO water and ran phosphate tests on each one. Suprise, suprise, guess what one turned the water totally dark blue/black upon doing a phosphate test? PH DOWN was the culprit!

It isn't the sodium bisulphite, the "PH down" possibly contains a phosphate buffer as well (disodium hydrogen phosphate (Na2HPO4)/monosodium phosphate (NaH2PO4)).

One problem is that measuring phosphate levels is a bit of a complex subject. If you live in the EU you will have high levels of orthophosphate (PO4---) in your tap water, because the water companies add it. This is to precipitate out any lead (Pb) or copper (Cu) in the water supply and is known as PIMS (phosphate induced metal stabilisation). They also add sodium hydroxide (NaOH) to raise the pH, this is because insoluble calcium phosphate compounds are formed at above pH7, precipitating phosphates out of the water column. This may also be what is happening in the tank, if the "pH down" is lowering the pH below pH7 phosphorus will re-enter the water column as the calcium phosphate dis-associates back into calcium (Ca++) and phosphate (PO4---) ions.

My suggestion would be to throw away the "Tetra Phosphate-Minus", Phosphorus test kit, and the "pH down", none of them are doing any good at all in improving your water quality. This may seem a bit extreme, but whatever you may read else where on the WWW:

1. You cannot control algae by reducing phosphorus levels, you will always have enough phosphate to support algal growth in your tanks.
2. Phosphate itself isn't toxic to fish, and we can't test for it reliably (as you have found), even in the lab it is difficult to get accurate values

All the compounds you add to the water, even if they reduce pH, raise the conductivity, and high conductivity ("salty") water is no better than alkaline water for your plecs.

The easiest way to lower phosphorus is to feed more live food (dry food tends to be high in phosphates), and have growing plants in your tank, as phosphorus is one of the 3 macro-nutrients that plants require in large amounts (although in much lower levels than nitrogen (N) and potassium (K)).

cheers Darrel

 

[Mooo]

Brilliant reply, Thanks Darrel , Even I could understand that
I always advise against buffers, More trouble than they will ever fix..:/

 

[dw1305]

Hi all,

I always advise against buffers, More trouble than they will ever fix..:/

Pretty much my view as well.

Even I could understand that

Thanks Moo, I must be getting better at explanation. I might even have another go at "pH and buffering", hopefully in terms that make a bit more sense next time.

Ekso, I should have asked what "the phosphate crisis" was? and whether you have an alternative source of water. I'm lucky in that I live in the SW of the UK, where it rains a lot and I can use rain-water (phosphorus doesn't have a gaseous phase, so rain-water will be phosphate free).

cheers Darrel

 

[Ekso]

Hi all,


My suggestion would be to throw away the "Tetra Phosphate-Minus", Phosphorus test kit, and the "pH down", none of them are doing any good at all in improving your water quality. This may seem a bit extreme, but whatever you may read else where on the WWW:

1. You cannot control algae by reducing phosphorus levels, you will always have enough phosphate to support algal growth in your tanks.
2. Phosphate itself isn't toxic to fish, and we can't test for it reliably (as you have found), even in the lab it is difficult to get accurate values

All the compounds you add to the water, even if they reduce pH, raise the conductivity, and high conductivity ("salty") water is no better than alkaline water for your plecs.

The easiest way to lower phosphorus is to feed more live food (dry food tends to be high in phosphates), and have growing plants in your tank, as phosphorus is one of the 3 macro-nutrients that plants require in large amounts (although in much lower levels than nitrogen (N) and potassium (K)).

cheers Darrel

Thanks for the reply!
The "crisis" turned out to be nothing because it was simply false testing due to the pH down throwing off results, but before I figured that out, my phosphate tests were literally off the charts, even after multiple water changes and phos-minus.
Here's a bit more information about my tank.
75 gallon

Filtration = 1x Fluval 306 70 gallon canister + 1x Whisper ex 55 over the back

Filtration Media = Fluval Carbon, Fluval Clearmax, Seachem Phosgaurd, Nitrazorb, Fluval Biocubes, Varying coarseness of foams ( for big flotsam )

Stock = 5x Mollies, 1 black shark, 1 redtail shark, 1 tiretrack eel, 1 black ghost knife, 1 polypterus sengalus, 2 (small) angels, 4 glo-danios, 1 Ancistrus sp, 1 Hemiancistrus sp. L128, 1 Sailfin Pleco (L-83), 1 Panaque maccus L104.

Heaters= 2x Fluval E-300s

Substrate= Mixture of black small gravel + brown fine sand + laterite mixed in

Plant stock = 10+ various anubias, 5+ very large amazon swords, 3x moneyworts, 7 (varying sizes from small to very large ) mondo grasses, 3x small marimos.

Temp = 75.5 - 78.5 ( don't have a chiller, room temp raises tank temp sometimes, try to keep it at 75.5)

Ph = currently, 7.5, target Ph = 7.0

Ammonia = 0ppm
Nitrites = 0ppm
Nitrates = 0ppm - .5 ppm (depending on time from last WC)
Tds = ? ( no idea, don't have a tester )

Food = Xtreme brand Spirulina-Krill flakes, Omega one Supper veggie red seaweed sheets ( 1 per week ), Xtreme brand concentrated algae wafers, blanched cucumber, occasionally beefheart cubes , live feeder ruby red fish ( under 1 inch long, 10 in tank a week, as the eel and sengalus destroy them as fast as i put them in )

OK, Now I know i could spew more info on lighting, water flow direction etc, but let's just assume I have ample lighting ( I do... lots of it), and ample water flow ( again, i do, lots of it).

Also, It should be noted, Many of these fish are temporary, while not large now, I am quite aware a good chunk of them , the angels, black ghost, tire track eel, black shark, etc are going to get to be big fellas. As they grow I shall re-home them as neccesary. Currently all my fish have plenty of individual territory including flagstone caves, plenty of bogwood/mopani/malaysian and plant cover. I have not had any issues with aggression nor feeding to date (6 months up-time in this particular tank).

That all being said, IF you use the gallon to inch ratio ( which I personally think is "whooey" as each fish is different and situation is varied ), My math says I am only 78% stocked. Anyways, Now with all that information... my question is this...

How do I get my pH down to a more comfortable range for the plecos without use of buffers, and with the information provided am I "doing it right" thus far? I have only recently gotten into fish and immediately fell in love with the plecos... what can I do at this point to optimize my tank's overall health and their happiness.