• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

Using Phosphoric acid

Simon

Simon

Member
Joined
6 Jan 2008
Messages
55
Location
Essex
I'm currently cycling a planted tank for discus. My local tap water has a high ph of 8.5 after 24 hours of circulation. So I am using phosphoric acid with weekly WC's (8ml 81% in 180l water) to bring things down to around 7.2

A question for the scientists on here: Would the acid be adding phosphates to my water?
 
Richard Dowling said:
I cant answer your question about the phosphates after dosing but I have done brief courses on water treatment. Where abouts do you live? I was quite surprised at the 8.5 pH, usually the water comes out of the treatment works in the 7.0's.
Click to expand...
Chelmsford. Must explain the Essex sense of humour.[DOUBLEPOST=1398231448][/DOUBLEPOST]
Richard Dowling said:
I cant answer your question about the phosphates after dosing but I have done brief courses on water treatment. Where abouts do you live? I was quite surprised at the 8.5 pH, usually the water comes out of the treatment works in the 7.0's.
Click to expand...
Chelmsford. Must explain the Essex sense of humour.
 
Phosphoric acid is a strong acid and is toxic to fish. It is a lot more toxic than a pH of 8.5. That's a certainty. You should leave your pH alone because discus do not really care what the pH is. They do care about being maimed by toxic acids though.

Cheers,
 
ceg4048 said:
Phosphoric acid is a strong acid and is toxic to fish. It is a lot more toxic than a pH of 8.5. That's a certainty. You should leave your pH alone because discus do not really care what the pH is. They do care about being maimed by toxic acids though.

Cheers,
Click to expand...
Isn't phosphoric acid used in a lot of fizzy drinks and food stuffs? I used it for years to lower the ph when I kept discus some years back with no problems at all. I also know that the local Malaysian discus importer also uses it. I appreciate care is needed, which the water change process gets, with digital checking of PH, TDS and temp in the main tank and WC water.
 
Yes, cola uses phosphoric acid to give it that tangyness and sugar is added to balance the flavor. Phosphoric acid is also used to remove rust from metals.

Cleanliness is much more important than pH value, which is meaningless just by itself. If this is a CO2 injected thank then the pH will naturally fall by quite a lot, and even if it's not injected, the tank will produce acids which will drop the pH. In any case, fish really do not care about the pH number itself so really, there is little point in trying to manipulate the tank parameters to achieve some arbitrary value. You can get into trouble using acid buffers depending on the other characteristics of the water.

Cheers,
 
Thanks ceg4048 I appreciate your advice.
The tank is not C02 injected, but gets a dose of Easy Carbo and ferts daily. Planting is more on wood than substrate, so not really much in the way of fast growing, nutrient sucking plants. I'm assuming using phosphoric acid is also going to give me a spike of phosphates with each weekly WC?
 
I found sulfuric acid works better (battery electrolyte).
You must monitoring KH level. If you add too much acid and your KH goes to 0, then any more acid will drastically drop ph. Also don't measure ph straight after adding acid as it will always be lower at the beginning due to co2 production. Keep KH no lower than 2 degrees.


Wysłane z mojego GT-I9300 przy użyciu Tapatalka
 
Hi all,
Simon said:
Isn't phosphoric acid used in a lot of fizzy drinks and food stuffs?
Click to expand...
It is, H3PO4 is "E338". It differs from hydrochloric (HCl), or sulphuric (H2SO4) acid, by being a weak acid.
In the case of H3PO4, you added 3 x H+ ions (acids are "H+ ion donors") and one PO4--- ion (PO4--- is a base and why H3PO4 is a "weak acid").

The problem with all these additions is that you are adding things to the water and Discus come from water with virtually no salts of any description.

You can think of it a bit like making tea, you start with water and you add a tea bag, this gives you "black tea", which you might make more palatable by adding milk (white tea) and sugar (sweet white tea), but each substance you add takes you further from the original water.

If your tap water is very hard I don't think acids will really help long term and I would cut my tap water with 3/4 RO or rain-water. There is nothing to stop you then adding a small amount of phosphoric acid (or hydrochloric etc.) to lower the pH.

cheers Darrel
 
I'm actually tempted to try C02. My only concern is that most discus tanks I have seen with C
dw1305 said:
Hi all, It is, H3PO4 is "E338". It differs from hydrochloric (HCl), or sulphuric (H2SO4) acid, by being a weak acid.
In the case of H3PO4, you added 3 x H+ ions (acids are "H+ ion donors") and one PO4--- ion (PO4--- is a base and why H3PO4 is a "weak acid").

The problem with all these additions is that you are adding things to the water and Discus come from water with virtually no salts of any description.

You can think of it a bit like making tea, you start with water and you add a tea bag, this gives you "black tea", which you might make more palatable by adding milk (white tea) and sugar (sweet white tea), but each substance you add takes you further from the original water.

If your tap water is very hard I don't think acids will really help long term and I would cut my tap water with 3/4 RO or rain-water. There is nothing to stop you then adding a small amount of phosphoric acid (or hydrochloric etc.) to lower the pH.

cheers Darrel
Click to expand...

That's a good analogy Darrel. Thank you for your thoughts. No one has answered my original question....will using phosphoric acid add phosphates to the water?

I am going for Stendker discus, which, apparently have been raised in hard water for 45 years and are quite used to it. My tap water is 12DH which seems to be around the same as Stendker and Devotedly Discus. Just the PH is sky high.

There seems to be a lot of fear with adding acid to discus water, but C02 suggested as an alternative. I know 2 discus keepers who have gassed a tank full of adults, but no one who has lost fish through using acid as a Ph reducer.

If they are going to be happy with a Ph over 8 then i would, of course, much rather keep things simple and consisstant.
 
Very suspicious of my Ph meters accurracy, so just did a new 2 point calibration. Looks as though I'm .5 over on the readings. Leaving a glass of tap water overnight for a new test. Anything below 8 and I'm happy to leave well alone and let the future maturity of the tank pull it down a bit.
 
Hi all
will using phosphoric acid add phosphates to the water?
Click to expand...
Sorry I should have made that a bit clearer, yes it will. PO4--- is the orthophosphate ion that plants take up. In hard water what will happen to free PO4--- ions is that they will tend to be precipitated out of solution as "calcium phosphate complexes".
but C02 suggested as an alternative.
Click to expand...
The depression of pH by CO2 is a bit strange, it is caused by a change in the CO2 ~ HCO3- equilibrium and it doesn't change alkalinity, there is a bit of an explanation here: <http://www.ukaps.org/forum/threads/ph-drop-high-alkalinity.30384/#post-319698>.
I know 2 discus keepers who have gassed a tank full of adults,
Click to expand...
I'm a non CO2 user for this reason.
I am going for Stendker discus, which, apparently have been raised in hard water for 45 years and are quite used to it. My tap water is 12DH which seems to be around the same as Stendker and Devotedly Discus. Just the PH is sky high.
Click to expand...
in that case I'd agree with the others and just ignore pH. In fact "ignore pH" is quite a good route for all non-CO2 users to follow.

cheers Darrel
 
Darrel - thank you, that's a great help and has clarified some thinking. The phosphoric acid is banished to the bin, mainly because it's going to lead to algae problems with a PO4 spike every waterchange.

I left a glass of water overnight and tested this morning with a re-calibrated Ph meter. Slightly better at 8.2, so my meter was potentially out by .3

I plan, when the discus are in, to only use Tropica Premium, 4 pumps a day in a 370L tank. Would the water column get enough phosphate and nitrates from the rich diet of the fish?
 
Stendkers are tough fish, we've abused them a lot (getting them to shows) and they took it all well. Just look at your plants, with low light levels fish excrements could be enough, if plants struggle/get algea add ferts. Personally i would go with big waterchanges often and add some ferts after that. If all is going well start to lower the wc gradually.
 
Edvet said:
Stendkers are tough fish, we've abused them a lot (getting them to shows) and they took it all well. Just look at your plants, with low light levels fish excrements could be enough, if plants struggle/get algea add ferts. Personally i would go with big waterchanges often and add some ferts after that. If all is going well start to lower the wc gradually.
Click to expand...
I'm cycling the tank at the moment. I took the filter media from a nano and added just a few rummy nose. I will build the companion fish over the next 8 weeks before adding discus. So, a small amount of Tropica Specialised going in every other day until the bigger, messy eaters arrive. Swords already looking good and throwing out new leaves. Tenellus looks a bit weak.
 
Just look at the plants for guidance. Doing large waterchanges is better for the discus then adding pH reducing stuff. Then if you plants need it you add some ferts, if you have a lot of plants i wouldn't even hesitate to add N and P, this won't harm the discus.
Should you want to recreate the biotope: no plants, very soft water and then little N/P, but adding plants you'll need ferts ( or a large river flowing through your tank).
 
Hi all,
Edvet said:
Just look at the plants for guidance.
Click to expand...
I'd go with Edvet's suggestion. You can either add a small amount of fertiliser regularly, or you can use the "Duckweed Index" approach <http://www.ukaps.org/forum/threads/low-maintainence-long-term-sustrate.14400/>, even when the fish are in place, you are probably mainly going to need to add N and K.

Although N: P: K are the plant macro-nutrients, plants need about 10x more N & K than they do P (and about 5x more P than Fe, Ca & Mg), all the other elements are micro-nutrients, and plants really do only need trace amounts (hence "trace elements").

In all cases I'd buy a pack of dry salts from one of our sponsors, it is likely to work out a lot cheaper in the long run.
<http://www.ukaps.org/forum/forums/aquarium-plant-food-uk.63/>.

cheers Darrel
 
Darrel - I have that floating plant in the tank. The shop I bought it from suggested watching the floating plant as well. They have some excellent low tech displays that have been running for years.

Dry salts I have never touched. Would this give me something compareable to the Tropica ones?
 
You must log in or register to reply here.
Back
Top