pH swings from C02 - Danger to fish?

[Aknickolai]

I have a 72 gallon bow front that is pretty heavily planted, stocked with various tetras and amano shrimp, C02 injection, EI dosing for the ferts, and about 3.5 WPG light.

The tank is running along great with the exception of small amounts of BBA, which I have been combating with excel spot dosing. I think I am winning that battle.

From what I have read it seems like the swings in C02 from my pH controller may be contributing to the BBA. So, the question becomes if I remove the controller (or set it much lower so it acts as an emergency safety device) how harmful are the resultant pH swings to the fish/shrimp in the tank?

I run a drop checker with 4 dKH water in it, and to get to the 20-30ppm range of C02 I end up dropping the tank pH from 7.5 to 6.5. If you only inject during the day it seems like too much of a change for the fauna of a tank to go through on a daily basis.

I read the other post on this topic a bit farther down the forum, but the resultant pH swings seem to go against everything I've ever been told on keeping happy fish. Has anyone ever done this with more sensitive fish like Discus and found it to be ok?

 

[VaughnH]

pH changes due just to adding CO2 don't harm fish. If you get too much CO2 and don't have enough water circulation, or have a tank that is too dirty, you may run short on O2 along with the high CO2, and that will harm the fish. This has been demonstrated by many people.

 

[Tom Barr]

Fish keeping does not add CO2 to control pH though.
They use buffers like baking soda.

When the pH drops fast, it's a sign of some cycling going very wrong in a fish only tank, when you add say 4 Kh more baking soda to a 2 Kh tank, the fish will die and the pH will shoot up fast.

CO2 is not the same.

Think about this thought question:

What happens if I do a massive 60-70% weekly water change when I add CO2 and have a pH of 6.2, and the incoming tap is 7.6?

How much pH change do I see over a few minutes?
About 1 full unit.

The KH is the same with respect to the tap water and the tank water.
So the osmotic difference is the same, CO2 is not a salt.

Now, think about what folks do using CO2 and in planted tanks with 50% weekly water changes......

Any reports of dead fish?
None.
Healthy happy fish and plants?
Yes.

I'll let you ponder the rest and see how pH, at least in and of itself is not really the issue, rather the KH/buffering systems that change rapidly, and thereby also by definition, change the pH, are the real issue with respect to fish health.

Fish hobbyist hardly know beans about GH, KH, and chemistry of the pH/KH/CO2 system as it is. And then only in relation to ambient, not fertilization with CO2 ppms.

So that causes myths and confusion.

Regards,
Tom Barr

 

[JDowns]

I think I understand the basics of why its the sudden swing in KH that is harmful to fish and not the swings in PH due to CO2 that are percieved to be harmful.

Sudden swings in KH directly effect osmotic pressure and the function of fishes gills and the ability to pass water across the cell membranes.

I'm sure there is alot more involved in the process including conductivity, buffering ability of the fishes blood, the swim bladder, etc.

Biology was never one of my strong suits, but I think I'm sorta on track.

 

[Aknickolai]

Thanks for the info! I'm no chemistry guru myself, but based on what you all said and a little help from google I think I'm pretty convinced the pH swings do to switching the C02 off at night won't hurt anything. The key for me was to do some research on osmotic pressure and salts. Thanks!

 

[Tom Barr]

And we all know that CO2 is not a salt.
It is easily moved in/out of the blood in fish.

Regards,
Tom Barr

 

[Uncle Rico]

CO2 fluctuation on algae growth

I was wondering the same thing since I recently put my tank on a timer and noticed that the PH rises significantly(to 7.7 from 6.7) overnight since the CO2 is off all night. Besides the fish(which I feel better about after reading this thread) I am also worried whether this will trigger algae growth. I have heard that fluctuating CO2 levels can trigger algae growth, so will having the CO2 automatically turn off at night contribute to algae growth?

 

[Tom Barr]

Since folks often reference Amano, he says it is Taboo, very rude to add CO2 at night.

I asked him personally, that was the response I got

Regards,
Tom Barr

 

[mattchuman]

ph swings dangerous to discus

Hey,
I have a 37gal, moderately planted, most Seachem additives for the plants and a cheap CO2 injection. I am getting PH ranges of 6.5 to 7.5. I have 3 discus, neons, siamese algae eaters and some cories. They all are fine. I will say that I believe my discus are tank raised and not wild caught. It is my plants that are getting blue green algae blooms. I am trying with out the CO2 to see how much of swings there are.

The Black beard algae is best controlled with a phosphate reactor and some sort of phosban type substrate. It was out of control in my tank. I used RO/DI and tap water on different ocassions (which only helps to grow bba) and now it is perfect, except for the blue green algae.

Hope that helps. I am in search of something to control my drastic PH changes too.

 

[Tom Barr]

Hey,
I have a 37gal, moderately planted, most Seachem additives for the plants and a cheap CO2 injection. I am getting PH ranges of 6.5 to 7.5. I have 3 discus, neons, siamese algae eaters and some cories. They all are fine. I will say that I believe my discus are tank raised and not wild caught. It is my plants that are getting blue green algae blooms. I am trying with out the CO2 to see how much of swings there are.

The Black beard algae is best controlled with a phosphate reactor and some sort of phosban type substrate. It was out of control in my tank. I used RO/DI and tap water on different ocassions (which only helps to grow bba) and now it is perfect, except for the blue green algae.

Hope that helps. I am in search of something to control my drastic PH changes too.

Most everyone here adds PO4 in the form of KH2PO4 to about 2-3ppm to reduce algae.

There is no correlation between BBA and PO4.
There is a huige correlation and BBA can be induced with less CO2 in any aquarium, regardless of KH or PO4 level.

If you believe that Excess PO4 at any level causes BBA, explain the many aquariums I and others have done for decades, and ADA's tap, as well as the sediment which also has high PO4?

I use tap and suggested using that in 99.5% of the cases, same for fish unless they have a very specific fish and goal.

The only way to control pH with soft water is adding baking soda and raising the KH. Good usage of light and CO2 will address any algae issues along with good dosing. It's not a question of limitation of algae, it's a question of good horticulture for aquatic plants. I've maintained this and have proven this concept for 15 years now with regards to algae and plants.

Plants want good CO2, not some pH specifically.
Fish don't care about pH swings because they are all CO2 related, and CO2 is not a salt.

You can kill fish with CO2 and the pH will also, change, but it's due to excess CO2, not the pH change directly.

Big difference.

This tank has 3 ppm of PO4, no issues with any algae.

This tank has 2.5ppm of PO4 added 2-3x a week!

And this tank has 2ppm added 3x a week:

How come I do not have BBA if PO4 and RO is the key there?
How can that possibly be correct if PO4 limitation is the key?
Riddle me that?

I also lack any BGA............

But my NO3 is at 20ppm, there is also no glass algae of any sort like GSA(same reason as BGA with higher NO3 and PO4 for GSA).

ADA's tap is around 0.5ppm of PO4, and they do weekly (or more) 50% water changes etc. ADA aqua soil is very rich in P relative to N.
So there's plenty of P in the aquarium there and in my tanks.

Regards,
Tom Barr








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[RlxdN10sity]

I know you must be tired of addressing the myths of nutrients causing algae problems by now, but ya kinda nailed that guy, considering its his first post and all. Gorgeous tanks by the way.

 

[easttech]

Just wanted to post what has been happening in my tank and concerns I had with Ph swings and Discus and fish in general. I am only 8 weeks into my 300 gallon planted tank. Thanks to Tom and Gerry (wasnt that a cartoon?) I have gooten a good foundation from which to build. Thanks to them and others for their paitience and advice.

In any case I was planning a planted Discus tank. Co2 injection. Been working co2 issues, large reactors, nw pumps and you name it to get enough co2 into my tank. That has all been settled for a few weeks and have recently started adding 4-5" Discus. This was aalso a change since I was originally, due to cost thinking smaller fish, but then after reading all about the feed and WC required and overall required cleaniliness of rearing young discus I thought better of it and sprung for 9 larger fish. Although I have a controller I have opted for co2 on a timer. My ph swings from 8.1 at night to 6.9 during the day. I was concerned about the fish, especially discus and plants. Both Gerry and Tom kept telling me to not worry about it and concentrate on the co2. Just want to report I now have 4 fish that have paired off, one has spawned and is caring for the eggs the 2nd pair are preparing a site. This is all way beyond my expectations. I am following an EI fert scheme, I do 10% water change daily and a 30-50% weekly. My plants are doing well, not spectacular, but not wilting or dying off and producing new growth on some Glosso and Anubias, swords are easy and also doing well with new growth. I am now in the process of monitoring and will make some slight adjustments to lights and ferts over the next few months to get it really dialed in.

So ph swings have not hurt my fish one bit. 2 discus spawns after only a week in the tank aint bad. I am sleeping way better at night!

 

[Tom Barr]

I know you must be tired of addressing the myths of nutrients causing algae problems by now, but ya kinda nailed that guy, considering its his first post and all. Gorgeous tanks by the way.

They'll live, I'm sure. I've had plenty pile on me for such things on line or in person, but I chose to not take it personally,....because it was not personal.
That's a choice they or anyone can chose to make......or not.........If it's not clear, and you THINK it is personal, then ask the question directly and stop guessing.
Then you know.

Pretty simple. I've long attacked the idea, but not the person.
There is a BIG difference.

 

[Tom Barr]

Just wanted to post what has been happening in my tank and concerns I had with Ph swings and Discus and fish in general. I am only 8 weeks into my 300 gallon planted tank. Thanks to Tom and Gerry (wasnt that a cartoon?) I have gooten a good foundation from which to build. Thanks to them and others for their paitience and advice.

In any case I was planning a planted Discus tank. Co2 injection. Been working co2 issues, large reactors, nw pumps and you name it to get enough co2 into my tank. That has all been settled for a few weeks and have recently started adding 4-5" Discus. This was aalso a change since I was originally, due to cost thinking smaller fish, but then after reading all about the feed and WC required and overall required cleaniliness of rearing young discus I thought better of it and sprung for 9 larger fish. Although I have a controller I have opted for co2 on a timer. My ph swings from 8.1 at night to 6.9 during the day. I was concerned about the fish, especially discus and plants. Both Gerry and Tom kept telling me to not worry about it and concentrate on the co2. Just want to report I now have 4 fish that have paired off, one has spawned and is caring for the eggs the 2nd pair are preparing a site. This is all way beyond my expectations. I am following an EI fert scheme, I do 10% water change daily and a 30-50% weekly. My plants are doing well, not spectacular, but not wilting or dying off and producing new growth on some Glosso and Anubias, swords are easy and also doing well with new growth. I am now in the process of monitoring and will make some slight adjustments to lights and ferts over the next few months to get it really dialed in.

So ph swings have not hurt my fish one bit. 2 discus spawns after only a week in the tank aint bad. I am sleeping way better at night!

Tom and Gerry are bit less.....well......violent and a bit more mortal..and nowhere near as funny.

Getting nice larger fish is a good idea I think. This way you get to enjoy the nice large fish right away, but something can be said for raising your own.
Several folks I've helped or worked for have had Discus breed, including myself in planted tanks.

Discus zealots(Some of which are my good friends or clients, so you keyboard tender foots can get off the high horse) have long stated that that high CO2 is terrible for them, and then it was high NO3 and then it was plants and "phytotoxins".
I've heard so much rubbish spanning 20 years now. But.......as more folks come through and demonstrate that these claims are false, we can safely verify that those hypotheses are falsified, thus must be rejected. It does not say "what" causes problems for Discus breeder's, owners, it only rules out what it cannot be independent of other factors.

No one bothers to actually test their hypothesis, but then wants to passionately argue with me over the topic. Then I come off as harsh
Heheh, I am evil. But they set themselves up to make the error in logic to begin with by guessing.
I do not want to set myself up, I'm wrong a lot, but I already know that, so I take steps to avoid such mistakes.

So, when you end up proving your original premise wrong/falsified, you change your own views. That's much more powerful and instructive than agreeing with everyone and playing all nice.
I come off crotchety for a reason.