nitrifying bacteria at low pH

  • We are currently upgrading MFK. thanks! -neo
the_deeb;1590560; said:
Went out and bought a test kit and got some odd results.

Tap water: pH 7.2, KH 40ppm, GH 150ppm

Tank water: pH <6, KH 0ppm!, GH 75ppm

So clearly, lack of buffering appears to be the problem here, as ShadowBass suggested. But what's causing the drop in KH and GH between the tap and tank?

I'm going to take your advice and add crushed coral to my filters. Do you have any idea how much to add?

Also, I do water changes with a python directly into the aquarium. How do you suggest I go about treating the water with baking soda? Should I just add it to the tank during a water change? That seems like it could cause big swings in KH.
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The best way would be to use garbage cans to store the water, add baking soda and let it adequately dissolve, run crushed coral in your tank and do water changes out of the garbage cans using a pump.

Not sure how well it will work adding directly to the aquarium, but it should be better than nothing. You'd want watch closely and do water changes accordingly since it is NOT going to raise your pH. It's only going to buffer the water and keep it from dropping further. The water from the tap is going to raise the pH a bit but maybe not by much. You may have to do several water changes, utilizing baking soda, to get it back to normal and keep it there.

Not sure on the actual amount of baking soda. I use RO right, just because it's convenient to me. I don't have to buffer my tapwater though, so I only use that on RO water.

This site (http://www.drhelm.com/aquarium/chemistry.html) says 1 tsp for 50 liters (around 13 gallons) will raise kH by approximately 4 dH without major effect on pH.

I know several users on here use baking soda to buffer, does anyone have any personal experience with dosing it?

For the first water change I would dose for the whole aquarium since you essentially have no buffering in there. 7.5 teaspoons would be correct for 100g according to the above article. (Do a water change and THEN dose, do not dose and then wait to do a water change).

Watch the kH closely on your aquarium and add buffering as necessary. For subsequent water changes add the correct dose for the amount of water you're taking out.

Odd that no one has posted with personal experience using baking soda (Like I said, I use RO right). I've seen several people post in threads before mentioning it. Maybe if you post in the Setup and Filtration section you'll get more advice.
 
just be sure not to raise it all at once you will pH shock your fish and they already seemed stressed, also higher pH = more of the toxic form of ammonia
i had the opposite problem my pH sits at around 7.6 and is liquid rock for hardness. trying to lower the pH outside the tank took a triple dose of pH down and it still rebounded. fortunately this is an acceptable pH for the fish i have though not ideal,so I decided live with it and not risk constant pH changes .
I wish you better luck
 
Thanks for the advice, that really helps. Your advice may allow me to understand what is going on in my tank. I'm running ten aquariums at the mo but this is the only one with a prob for various reasons I think I now understand.

I'm going to measure my parameters in tap and tank as they stand right now and repost the results rather than posting what I think they were last week/last month etc.

I do understand that I should not try to change the pH by more than 0.2 pH units per day to minimise fish and bacteria stress.

Maybe here's one where we can try the baking soda!

I understand that the relationship between pH and hardness can be complicated but the pH is the negative log of the concentration of hydrogen ions in the water and KH is the concentration of carbonate and bicarbonate anions in the water. KH is not total hardness.

A higher KH might help stabilise the pH above pH 6.0.

Don't mean to show off chemistry, trying to get it right and please correct me if I don't!
 
just tested my tap water and that was interesting. It's below 17.5ppm or 1 drop so my test kit just goes to its endpoint! Was about 3dKH last time I looked. So is the tank and pH is below 6.0. How much below I'm not sure as this is pretty much off scale.

Thought dodgy test kit? So tested reef (soft corals) tank and got 8dKH or 8 drops before endpoint so the test kit is OK.

Sounds like i'm going to be making Kasselwasser...
 
I have several 50L food grade plastic barrels I use for marine water changes. I can mess around with the pH and hardness in these and then make some up to powerhead over into the tank.

As several people around say, it's not keeping fish, it's keeping water!
 
http://fins.actwin.com/mirror/begin-chem.html

There's another article.

soggydrysuit, your method with the plastic barrels would be the best.
The values aren't necessarily going to change the same for everyone, so you'll have to experiment to get it where you want it. Test the pH and kH until you get it where you want it.
 
Similar to making up salt water for my marines. I've a barrel full of water at pH 6.5 and about 3dKH. I'm leaving it with a powerhead and heater in to see what happens over a few days as the CO2 from the air gets at it. Then I can do a barrel per day. Should be slow enough.

All the fish in that tank are soft water lovers but probably not pure carbonic acid!
 
How long does it normally take for crushed coral to release its carbonate? I added a few cups to my canister filters about 48hrs ago and have yet to see a change in my KH.

I decided to try just the coral initially to see how much that would improve my buffering capacity. I live in a pretty small apartment so I can't have garbage cans of water sitting around (my wife already gets annoyed enough at me for not cleaning up all the other fish related junk :) ) and I don't want to take the risk of massive KH swings from adding baking soda directly to the aquarium.

Once I figure out what KH my tank will equilibrate to with the crushed coral I might try reducing the size of my water changes and adding a little baking soda in to compensate for the low KH of the water that I'm adding back in.
 
the_deeb;1587933; said:
I've come across a few websites that state that Nitrosomonas growth is inhibted below pH 6.5 and that all nitrification stops if the pH drops to 6.0. I'm wondering if this is the problem with my aquarium - the pH is 6.0 or lower and I'm seeing ammonia spikes despite having established filters, a relatively small bioload and light feeding.

I think I'm going to buy a KH test kit and add some crushed coral to my filters to try to raise the pH.

My question, is what do discus breeders (or other people who use low pH setups) do? I can't imagine there are constant ammonia problems in discus aquariums.
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This reply diverges from the KH and PH question, but I'll answer the ammonia problem. When PH is below 7, ammonia(NH3) will become a non-toxic ammonia ion(NH4). NH3 becomes NH4 because the low PH means more H ions which allows NH3 to bind with another H atom; this process also occurs in a tank with PH>7, but not in great quantity. I THINK that bb can't convert NH4 into nitrite; so nitrification does stop.
 
Did you figure out what is lowering your alkalinity?

Lot's of different things can reduce the minerals that make up your alkalinity..

Namely Driftwood and Nitrifying Bacteria..

Nitrification lowers Alkalinity.. and you don't have much.

Need a buffer, like crushed coral. R/O Right, etc..

Also, do you 'gas out' your water when you do water changes? If you submerse your python you could be forcing in alot of water that has no O2 in it, but that wouldn't explain the lack of alkalinity.
 
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