# Why would a Phosphate Buffer be bad for plants?



## wellbiz (Aug 6, 2003)

I went to their website and they dont explain why you cant use it and what the chemicals used in it are, according to the MSDS they are trade secrets. 

However it is a know fact if you add a phosphate based ph modifier to a planted tank with high light you are going to get some pretty serious algea problems. I am not sure how C02 injection would play into this situation as you are lowering the ph already and modifiing the waters buffering ability and I suspect hardness too... I suspect another poster will have more info than I can provide....

Jason


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## Rex Grigg (Dec 10, 2002)

It's pretty much phosphoric acid. And adding it to a planted tank does a couple of things. It invalidates the kH/pH/CO2 chart that many of us rely on. It boosts phosphate levels up so high that algae problems are sure to follow. 

Why do you think you need a pH of 6.5? What is your starting pH and do you know how much kH you have? Do you have CO2 injection?


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## anonapersona (Oct 19, 2002)

I've used a phosphate based ph adjuster and I added about 1/3 of the amount that you would use to adjust the pH on my tank and got phosphate readings off the chart for 3 days, then they went down. I got a bit of hairy black algae started on some of the plants I cut from that tank at the same time, maybe the fish were keeping it under control in the tank. 

Even though the phosphates were sky high, the pH just barely moved, I'm sure that by the time the pH moved more than a fraction you would be putting in so much phosphates that something would have to go crazy.

I'm using that pH adjuster to add phosphates to the tank now, dosing 1 teaspoon of sodium biphosphate in 120 ml at 1 ml per ten gallon tank (true volume 7.5 gallons), so the suggested 1/4 teaspoon of dry chemical in a ten gallon tank would get you something like 30ppm of phosphates....a bit higher than anyone would suggest for a planted tank!


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## NeXuZ (Dec 15, 2003)

Thanks everyone!

Rex, my PH outta' the tap is around 7, so i dont really ave to change it at all, as i said, it was a gift. I have no idea what my KH level is because i've been away for a couple weeks and im going away later today for a week, my tank is empty....now  I gave all my fish back to my LFS cuz i want to start a SA Biotype, so a PH of 6.5 is perfect for Angels, most tetras and 4 rams....and then a couple other that the levels dont bother as much.

Thanks a lot guys (and gals), so i guess using it will be a no no, that's ok i have peat moss in their anyway so it should bring my PH and KH down a bit, it sais 8% reduction of KH on the Eheim peat moss, so i'll try that.

Thanks, 
NeX


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## Rex Grigg (Dec 10, 2002)

Did you test the pH out of the tap after the water had rested for a minimum of 12 hours? It' not uncommon for tap water pH to change up to a full point after the dissolved gasses have escaped.

As for the pH of 6.5 being perfect for some fish. Hogwash. Unless you are trying to breed them most all fish can adapt to most water. And you really need to know what your kH and gH number in your tap water are before you start going "water warrior" on us. And normally the best way to reduce pH in a planted tank is though the use of CO2.

anonapersona,

I'm sure you know that the sauces of a pH adjusting chemical depends on the buffering capacity of your water. But I wanted to explain it to those that don't understand.

If you have tap water with a high pH and high kH you have water that has a lot of natural buffering ability. If you try and use something like Proper pH 6.5 you will not be successful. The pH may drop for a short while and then bounce right back up due to the buffering ability of the water. These pH swings are one of the most harmful things you can do to your fish. For a more in-depth study of water chemistry I suggest you head over to http://www.drhelm.com/aquarium/chemistry.html


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## anonapersona (Oct 19, 2002)

Yeah, Rex, I do realize that and it is good of you to point that out to others. 

The *very* rough numbers of 30ppm with 1/4 teaspoon dry sodium biphosphate in 7.5 true gallons of tank water I posted were just to give someone an idea of how much phosphate "the recommended starting dose" might be putting into the tank. That ought to hold, even if the reusuting pH movement was larger than I can see in my tank with moderate buffering, KH = 7 to 8.


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## 2la (Aug 18, 2002)

It's not just the pH swings: People often don't realize that in their efforts to drop the pH for fish that prefer soft, acidic waters, they actually produce water with a very high TDS (due to all the additives) that is much _worse_ for their fish--regardless of the pH!


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## Rex Grigg (Dec 10, 2002)

Good point 2la.


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## GulfCoastAquarian (Jul 30, 2002)

And on top of all that - ProperpH binds heavy metals, rendering Fe, Mg, Ca, K and many other minerals useless to plants.


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