pH falling

[mpg]

i'm a little worried that my pH is getting too low.  it's now below 6.2.  the danios and white clouds are not that sensitive to pH, but i would feel better if i could at least stabilize it at 6.5.

i'm thinking the cause might be the fact that i recently added some plants which have prevented me from vacuuming the gravel as well as i used to.  although there hasn't been any ammonia since the end of cycling.

i don't like to 'rock the boat' by adding chemicals.  is there something else i can do?  more aeriation?  less aeriation?  more plants?  fewer plants?

 

[ryuken168]

What time do you test your PH, cause in the morning is lower when you just turn on the lights and higher in the end of the day. Only if you have strong growing plants in your tank. If your PH does change then you have alot of CO2. Plants does rise and lower PH like in my tank it's 6.4 to 7.2 difference.
If you test both times and same reading then your nitrate level is high. Water change will solve that problem or add more plants, also don't overfeed.
NYC tab water is neutral 7.0 so adding chemicals will rock the boat if thing get back to normal.
Worse comes to worse you can add baking soda. That will easily rasie PH. But test the amount first in a bucket.
Also driftwood lower PH.

 

[RedTurquoise]

Are you using any C02? Do you have activated carbon as filteration? What is your kH/gH?

 

[mpg]

my plants are slow growing low-light plants.
i always test in the evening, but i'll try it at different times.
i do water changes twice a week, but it doesn't have much of an effect on the tank pH.  (the tap water tests as 7.0).
i don't add any CO2.  
i do use activated carbon.
and i don't own a test kit for kH/gH, but NYC tap water is typically soft.

the only other thing i can think of is that i have some beach rocks (boiled and soaked) in there.

 

[RedTurquoise]

I have heard that activated carbon will decrease ph especially if your water is soft. Maybe as a test, take the carbon out of a couple of days and see what happens.

 

[Framer]

You really need to purchase a KH test kit. What has most likely happened to your tank is called biogenic decalcification. This happens when plants don't have sufficient CO2 available. Plants will strip calcium carbonate (KH) from the water to get enough carbon to perform photosynthesis. In your case if the KH was already low, then once the plants stripped the KH the pH would fall. Unfortunately without a proper buffer (KH in the 2 dKH range and above) your pH will continue to fall. Water changes will help, but if there is little KH in your tap water then the plants will quickly strip that too, eventually your pH will sustain a serious crash.

Two things you can do to solve this problem.

1) Inject CO2, when plants have an ample supply of CO2 then the biogenic decalcification will pretty much stop. You could then most likely stabilize your tank by doing water changes.

2) Add baking soda (sodium bicarbonate) to increase your KH and pH and thereby replacing the buffer you are currently missing. Don't get to hung up on the phrase of "I don't want to add chemicals to my tank"...many poor websites preach this bad information. Water, plants, and animals ARE a combination of chemical elements. The important issue is to add the correct and needed chemical/elements at the proper dose and time. Here's how to raise the KH of your tank water.

To one cup of water add 1/2 teaspoon of baking soda per 100L (25G) of tank water. Dissolve the baking soda in the cup of water then add the water to your tank. This will raise the KH approximately 1 dKH and increase the pH about 0.2. Wait one hour then test again for pH and KH to measure the effects. If the KH and pH increased as predicted then wait 24 hours and repeat, if the KH and pH didn't increase (this is possible but not likely unless a strong acid is present) then repeat and retest in one hour. Never adjust the KH by more than 2 dKH per day or raise the pH by more than 0.4 per day. This is very safe and effective. Raising the KH will add the buffer needed to stabilize your pH which will greatly help with the health and vitality of both fish and plants.

HTH

 

[ryuken168]

Now that's what I'm talking about. Excellent  *thumbsup2* info Framer. You nailed it on the spot. *crazysmiley*

 

[mpg]

"Don't get to hung up on the phrase of "I don't want to add chemicals to my tank"...many poor websites preach this bad information. Water, plants, and animals ARE a combination of chemical elements."

your point is well taken framer.  i should have said that i don't like adding chemicals that i don't understand what they do.  and your explaination helps me understand it a great deal.

on the other hand, i tried adding a short 1/4 teaspoon of baking soda (for a 10 gallon tank).  and it took the pH up to 7.4!!  a larger swing than i wanted.  a quick water change brought it to 7.2.  and i figured i'd better wait until tomorrow to do anything else.

i'll let you know.

 

[mpg]

so...  the next day it was down to 6.8.  and now it's back down below 6.2.  

are there other options?  the baking soda idea swung the pH more thank i would like, and didn't seem to have any lasting effect.  the way i understand it i am looking for a consistent way to add a buffer since my water is so soft.  if i add baking soda with every water change will the pH swings eventually stabilize?

i hadn't planned on doing any CO2 injection because of the equipment clutter involved.

 

[RedTurquoise]

What kind of fish do you have? Another test that you could do is test your tap water after it has been sitting for 3 days. Another test is kh/gh! It is hard to stabilize the ph if you dont know what the kh is.

i hadn't planned on doing any CO2 injection because of the equipment clutter involved

Clutter? What clutter? All you would have is a C[sub]O[/sub]2 cylinder and some air tubes into your tank.

 

[RedTurquoise]

What has most likely happened to your tank is called biogenic decalcification. This happens when plants don't have sufficient CO2 available. Plants will strip calcium carbonate (KH) from the water to get enough carbon to perform photosynthesis. In your case if the KH was already low, then once the plants stripped the KH the pH would fall. Framer

In actual fact, decalcification will increase ph, not decrease. How so? Plants will strip the C02 from the kh (Calcium bicarbonate). C02 decreases ph so if the plants are using it up, the ph will increase because the 'hardness' (carbonates) are left.

If in doubt, please read
http://www.thekrib.com/Plants/CO2/decalcification.html

 

[mpg]

ok so i'm thoroghly confused.  decalcification raises pH or lowers it?  CO2 raises it or lowers it?  thekrib.com articles were good, but too many formulas (for a hobby anyway).  i found another article at http://www.drhelm.com/aquarium/chemistry.html  which explained some things more simply.

let me recap my problem with what i've learned so far.  my pH is below 6.2.  i don't know the exact KH of my water.  but i know it's very low.  when i added baking soda it caused a big swing in pH and it was back to 6.2 in 24 hours.  in the mean time, i've read the simple explaination that the nitrification process (cycling) doesn't just end in nitrate, but also with carbonic acid.  so that's my acid source.  

if i had a higher KH the acid could be "absorbed" enough to not cause these drops.  so what's a good way to do that?  

i should also mention that i have a have a high waste load because i'm temporarily keeping danio fry in a netbreeder in the main tank because my rearing tank is crowded.  i'll be taking a tankfull of danios to my mom's elementary school in 3 weeks.

 

[RedTurquoise]

Well, I think that the best thing to do is get a hardness test kit and test your kh/gh.

C02 lower ph because the C02 reacts with the kh and forms carbonic acid. According to the krib articles, decalcification raises ph.

The best way to condition your water is in a separate container such as a barrel or another tank. This way you can test, adjust and test until you achieve the conditions you want. I still think that it could be your carbon in your filter. Try taking it out for a week or so.

 

[RedTurquoise]

mpg,
I can understand your confusion a little bit better now after reading the article that you posted.

Nitrifying bacteria, essential in the conversion of ammonia to nitrate also have a pH range preference, which is between 7.5 and 8.6.

Hmmm! I hate to be rude but that is BS! Maybe a typo and should read 5.5 and 8.6! Many tanks are below 7.5 ph and the nitrogen cycle is still functioning.

Excess waste product produces carbonic acid, which acidifies the water and lowers the pH.

Excess waste products produce ammonia/nitrite/nitrate. The nitrification process will also lower ph because...

the nitrogen cycle in our tanks produces nitric acid (nitrate).

This is true therefore it is important to do regular water changes and not allow nitrates to build up.

Othe than that, its a good article.

 

[mpg]

thanks for your help.  next paycheck i promise i will go out and get a KH test kit.  in the meantime, i'll take out the carbon, and i'll increase my frequency of water changes to every other day.  my tap water is an even 7.0 so eventually that should catch up to the nitric acid production.

but when i get the test kit and it tells me that my KH is low,  what do i do to remedy that?

 

[RedTurquoise]

First thing to do is get a hardness test kit like you mentioned.

Second is to leave your tap water sit in an open plastic container for a couple of days. Why? Tap water has C02 in it and it will dissapate causing the ph to alter. For example, my tap water is also 7.0 but if I aerate it for 3-4 hours, the ph goes to 7.6-7.8. This will be the water that is also in your tank.

Third, once we have determined hardness and ph (after aeration or letting it sit for a couple of days), we can take measures to solve the ph problem.

To remedy the problem of low kh, the article you had posted has some ideas. However, there is one little detail that will help and that is getting a large container and aging your water. This way you can adjust the properties of the water without causing stress to your fish like ph swings.

Keep us posted!  *thumbsupsmiley*

 

[Matt Nace]

[quote author=RedTurquoise link=board=freshwatergeneral&num=1030640452&start=0#13 date=09/12/02 at 06:50:48]

"Quote:Excess waste product produces carbonic acid, which acidifies the water and lowers the pH. "

Excess waste products produce ammonia/nitrite/nitrate. The nitrification process will also lower ph because...
[/quote]

That is true actually. The bacteria forming and feeding on the rotting material in the gravel uses oxygen, adding carbonic acid.

Red, It does lead to ammonia(your correct), but that article is like the mother of PH articles. I see nothing about ammonia or nitrItes ect. It was based on PH....or maybe I am not reading it right.
So talking about ammonia and such would not fit into their "Learn about water hardness, pH, gH and kH here!" article


Good find on the raising of the PH on biogenic decalcification. It makes more sense now. I also thought as Framer does(did?).

In fact, I had it happening to me, my water level became lower, and my Co2 was gasses out. All my plant's leaves were all white. Darn, wish I could have tested my PH to see what it was at.

 

[Matt Nace]

Hey red, read the articles on that site.

Goto carbon.

Carbon has phosphates?..wow..never knew that.
They also say it raises from a little to a lot.

hmmm.. *twirlysmiley*

 

[RedTurquoise]

Ahh! Must of jumped too quickly but from the point of hardness/ph and such, excess waste will produce carbonic acid via the respiration of bacteria cultures. Thanks for clearing that up. I didnt think in terms of bacteria 'breathing'. However, I would like to also mention the fact that plants will again be using it up therefore balancing out unless of course you have a lot more bacteria than plants and maybe that was the implication (excess). The nitrification process is very complicated complete with many factors that will affect the end result ie ph.

I read the carbon article. It is very informant and interesting. I dont use carbon and do not recommend anyone use carbon either especially in planted tanks. I have found articles about carbon being "bad"  *crazysmiley*! However, I guess it depends on the carbon one buys and being the cashstrapped hobbiest, everyone goes for the cheapest without knowing the problems that might occur.

What do you think about the ph of bacteria, Matt? Typo?

 

[Matt Nace]

Are you talking about what PH range the bacteria does best in?

Maybe they found the Ideal range is what they stated. We all know, however, that it works just as fine under 7 as well.  *twirlysmiley*

Carbon is a waste of money to me as well.  *crazysmiley*

Where is that article on bacteria going dormant?