There are some fish which like high pH, but I don't mollies are in that category. Mollies are pretty hardy critters and I would be surprised if the pH was an issue with them.

As far as how long to inject CO2 some people do it 24/7, others only when the lights are on. I myself, have tanks in both categories and don't have any pH issues with any fish I keep.

It sounds like you might just be starting out in planted tanks. Check out this site for some good info for starting out.

HTH.

 

I really doubt the DIY C02 would make your pH fluctuate enough to bother your fish. What size tank do you have? If it's really small (10 gallons or so) it might have a little more effect, but a tank bigger than that shouldn't see any big swings.

Since it's DIY, there isn't really a way to turn it on and off (at least not to my knowledge), so you'll be running it 24 hours.

 

Let me add, to make sure that your KH is 3 or better before injecting C02; this will help stabilize PH.

I have Molly's/Platys in a PH of 6.5 (at night) to 7.0 (day), this is with DIY C02 running 24/7.

 

30 gallon tank with mollies and baby mollies.....a kH of 5 and pH of 9 (I m pretty sure its 9)

I can turn off the co2 by unscrewing the bootle that inject the DIY co2

I want to inject some co2 for the moment to increase plant growth and to inhibit algal growth.....

How can I inject it slowly so pH doesnt fall rapidly?

 

Dropping the pH by a full point 8.0-7.0 won't hurt the fish. In fact, dropping it to the final lower value over the course of a few hours would be ok too. Fish get a lot less time than that when acclimating from the store to a home tank.

 

If your pH is really up to 9, that is getting into the harmful range for many fish. I would get it down to around 7 ASAP. Don't worry about the rapidity of the pH change. Or, did you mean that your GH was 9?

 

My pH is 9....I am sure about that....I never had a pH of 9.....I think a pH pf 9 and a kH of 5 don't match meaning that I think a kH of 5 is quite low with a pH of 9......what could cause this increase of pH?

 

If your pH is truly 9, you've got something in the tank which is leaching into your water. I would find it hard to believe any water source is dispensing pH9 water into their systems. That's for other more knowledgeable water people to chip in on. As far as the fish go, as HeyPK said, that's going to be much more harmful to your fish than a pH of 7 or upper 6's. Get it down!

 

I just have one question to add.
What is the pH out of your tap? If it's lower than your tank water, then it's definitely something in the tank driving it up.
I have a normal pH out of the tap of over 8, and none of the fish have had a problem with it in my non-C02 tanks, except for the fact that many won't breed in the higher pH. It does make it very difficult to grow many types of plants without C02, though.

 

At one time I was having a problem with my Bettas. I would loose a fish and had no idea as to why. I don't remember what made me think about it but I was always using a Low Range tester, I decided to get a High Range pH tester and discovered that my tap water (well) had a pH of 9 or higher. That is when I bought my RO unit and either used straight RO or mixed it with tap to bring the reading to a more reasonable number. I haven't lost a fish to that problem again.

 

I read this thread and tested my local water and found my ph to be above 8 out of the tap as well. Has anybody ever heard of lowering tap water using distilled white vinegar? I thought I had read that somewhere!

 

I have not, I would think that would be harmful to the fish. Using RO water mixed with the tap water would help.

 

Has anybody ever heard of lowering tap water using distilled white vinegar?

lol mmmmm... yummy.....pickled fish. But I usually only eat that on New Years Day!
Maybe you were thinking of distilled water, that will lower your pH also.
Steve T.

 

If your pH is truly 9, you've got something in the tank which is leaching into your water. I would find it hard to believe any water source is dispensing pH9 water into their systems.

http://www.ci.austin.tx.us/water/downloads/wqr_apr05.pdf

The average pH for Austin water out of the tap is 10.0. That's ten point zero. They do that in order to reduce corrosion in the pipes. The reason it is so high is NOT because of anything that is "leaching into" the water, but rather because they use a process that drives CO2 -out- of the water. Let that same water sit out in a container where it is exposed to the atmosphere, and it will draw in CO2 and stabilize at a pH of about 7.6. Seven point six.

It is my understanding that pH swings have little effect on fish unless those swings are tied to GH hardness, and that it's the osmotic pressure of hard water versus soft water on each side of the gill membrane that causes damage.

TW

BTW, why am I "off the scale"?

 

I've got tap water that has a GH of 0 and a KH of 10 or 11, all due to sodium bicarbonate, which is naturally in the well water here. It comes out of the tap with a pH of about 8.4 and the pH goes up to 8.6 upon standing, due to outgassing of some CO2. That is why I like to use rain water. Thank goodness it rains a lot here in central Mississippi!.

 

If you continuesly run an airstone and a DIY co2 and you have a pH level of 7 does that mean that there is enough oxygen in the tank for the fish to be ok?

When do you know that CO2 levels have reached a toxic dangerous level?

 

When do you know that CO2 levels have reached a toxic dangerous level?

If the fish are gasping at the surface, that's a sure sign, but you may not see that in time. Try not to go much over 30 ppm, and keep a close eye on your readings.

 

Wow! :shock:

 

If you continuesly run an airstone and a DIY co2 and you have a pH level of 7 does that mean that there is enough oxygen in the tank for the fish to be ok?

When do you know that CO2 levels have reached a toxic dangerous level?

Also make sure to keep your KH at 3 or above to give you a more stable PH. Don't let your PH drop below 6, I keep mine at 6.5.

Running a air stone will help reduce the amount of C02 in your tank from the surface agitation, so I would run the air stone only at night (lights off) if your C02 is on 24/7.