what makes pH rise?

[rubysoho]

ok, my fish are finally well again (no idea what happened to them, but two died and another was questionable) however my pH is still around the 7.6 area and i can not figure out why. i have no sea shells in my tank, nor is my substrate made of crushed shells or coral. I have tested tap water that has sat out for 2+ days and it was 7.0 ... i clean my tank each week, normally about 10-20% water change and sometimes 30%. what other factors could be raising my pH???? here are my tank stats:

ammonia = 0
nitrATE = 0
nitrITE = 0
pH = 7.5/7.6

none of the fish are acting as if something is wrong, but i am just boggled as to why my water in the tank is doing this. Also, my second tank which has zebra danios (who can tolerate the higher pH so i am not too worried for them) is having the same problem. The only thing that is the same between the two tanks are my plants. I have some anacharis, a banana plant, some camboba(?), and finally some narrow leaf ludwigia.

I'm stumped, my lfs guy is stumped, and a wonderful person who tried to help me on the unhealthy fish board here is stumped as well, which is why i have brought this question to this post section. Anyone have any ideas??? I am so confuzzled. plus i have a lonely cory cat (its partner was one of the two that died) and i want to have the pH under control before i introduce another fish. thanks everyone!!!!!

 

[tsaraber]

Make sure that the substrate you are using isn't altering the PH. I've seen somewhere that certain gravel can cause this so to make sure the bag says it won't alter the PH. You can check the gravel you have by placing some in a cup and covering it with household Vinegar, if it bubbles its calciferous and will raise your PH.

Also make sure you aren't missing any fish because if one of them has died it will cause the PH to rise if he isn't removed fairly quickly.

You can always plunk a piece of driftwood into your tank - it works really well for lowering PH.

 

[Fruitbat]

A couple of things might be affecting the pH of your tank. First of all...if you let tap water sit out for 2+ days it will absorb carbon dioxide from the air. Some of this will convert to carbonic acid in the water and drop the pH. I would be interested in finding out what the pH of your water is when it comes out of the tap.

Secondly...do you have any sort of rock in your tank for decoration? It is possible that, if you do, the rock might contain calcium carbonate (limestone) that will raise the pH of your water....sometimes considerably.

Of course....water with a pH value of 7.5/7.6 should be fine for just about any tropical fish. Even the acid-loving species of South American tetra and the alkaline-loving Rift Valley cichlids of Africa should be able to easily tolerate (indeed...thrive in) water with that pH. Unless you are attempting to breed such sensitive fish as Neon Tetras or Rams (which often won't mate in water that doesn't meet their requirements), a pH level of 7.5/7.6 shouldn't be a problem.

Unless the pH in your tank is experiencing wild swings (highly unlikely) then you probably don't need to spend a whole lot of time worrying about the pH of your aquarium.

Hope this helps a bit.

 

[BrianNY]

Fruitbat said the most important thing here. Your PH is fine. Newer hobbyists tend to think that the PH of their water is the most critical thing as far as keeping fish is concerned. The fact is, it is not. Most species can adjust to wide range with no problem.

PH is not something that can be isolated on it's own. KH, GH and CO2 will all have a bearing on the PH. I suspect that your KH and GH is high which will cause your PH to rise.

 

[rubysoho]

ok, to answer everyone's questions (i'll go in order to make it easiest):

i really do not believe it is my substrate, but since i don't have the bag anymore, i am going to double check it with the vinegar. and all fishies are accounted for

ok, to the second post, i tested my tap direct from the sink first, it was 7.0 as well, no change in the two day period. also there are no rock decorations, just a plastic stump with holes so the fish can hide. however, i am planning on chucking that for some driftwood soon. i'm not too concerned about the pH, except that my lfs has a pH of 7 and i didn't want to risk shocking any of the fish, even though i properly introduce them.

ok, finally, with the KH and GH, i don't have a kit for those... should i get one? or is it not as important as the kits most people suggest (nitrate, nitrite, ammonia, and pH)? thanks everyone!!!!

 

[tsaraber]

Honestly, if I were you I wouldn't bother with the KH and GH... You do have fairly decent tap water and as long as you do regular water changes and acclimate your new arrivals properly you shouldn't have a problem.

What I can't understand is how you have 7.0 tap water straight out of the tap, and it stays 7.0 when you let it sit somewhere outside the tank for two days. With my tap water it comes out of the tap at 7.0 (or something, can't remember exactly) but after leaving it sit for a couple of days the PH actually rises. I was told it had something to do with the CO2 leaving the water? Yet what Fruitbat says completely goes against that theory. Man this whole fish thing is confusing. 8O

 

[Fruitbat]

tsarber.....

What you describe is actually MORE likely than the scenario that I painted....the loss of CO2 could cause a rise in pH....though it probably wouldn't be particularly noticeable. What I proposed (absorption of CO2) would be more likely if you were using distilled water. I guess it is the old chemist habits that still come to the surface every now and then.

 

[tsaraber]

Thanks for clearing that up Fruitbat..

Very useful information considering we are using distilled water.

 

[rubysoho]

well i am still a little confused... after work i am going to get a small thing of vinegar to test my rocks. if it isn't the rocks (which i am pretty sure it isn't, but since i am a newbie, i have a good chance at being wrong) could it be too many plants absorbing too much CO2? the whole CO2 thing confuses me, maybe because i was never any good at chemistry (but i love biology!!!.. except when i have to use chem. formulas... yucky math! this is why i am a communications major now, hehe). btw, thanks for all the respnses!

 

[BrianNY]

Well, rubysoho (like the nic). I'm pretty certain it's CO2 gassing out of your tank that's boosting the PH. Especially if you're mixing with distilled water. I'll try and explain:

Like I said earlier, there's a relationship between PH, KH and CO2. It's KH that buffers your water and maintains a stable PH. There is CO2 present in your tap water, and your fish produce it as well in their respiration. The CO2 is in a disolved form. As your water circulates, especially with the aid of airstones and surface agitating filters, the dissolved CO2 gasses out and leaves the tank. This raises the PH. Conversely, if you were injecting CO2 (as in a planted tank), and your KH is low, the PH is apt to fall is not enough KH is present in your water.

whew...............make sense?

The fast is though, that your PH is fine just where it is. Fish can tolerate a modest swing which is what is happening in your aquarium.

 

[rubysoho]

thanks for taking baby steps with me to explain i kinda get what you are saying, but i think it is one of those things that with a little more experience i'll be able to understand. i was always one of those kids who loved the hands on stuff in school.

ok, i was thinking the other day about adding a small CO2 injector (the DIY kind) because i do have a lot of plants in the itty bitty 10gal tank (lately i've been dreaming about a 46 gal that i want... *sigh*)... do, if i have a decent level of KH (which i am going to try and get tested today) would the CO2 injection not only help the plants, but also maybe lower the pH some as well?

oh! and i just remembered, i noticed one of my plants getting a little brown on the edges (it is a difficult plant, and i don't think i have enough light for it, which i didn't think about when i got it), could that be increasing the pH? so many questions, so little time!!!

 

[BrianNY]

Why are you worrying about the PH at all?

 

[rubysoho]

well, not as much worried as trying to learn more i guess. i think it would be cool to try and breed, and knowing a little more on how pH works and how to work with pH is something that will come in handy.

 

[tsaraber]

Don't worry, I think I kinda know where you're coming from - been there, done that.

7.0 is the PH... No matter that with care our fish can get used to a higher PH, or we could just get fish that thrive in our PH - it's kind of a fun little challenge to see if we can achieve it. As long as we're careful not to do it at the expense of our babies.

Yes CO2 injection can lower your PH but I personally think it's overkill, especially in a small tank - not to mention it's just one more thing to clutter up your pretty tank.. In addition you run the risk of killing your fish if you don't get the CO2 just right. That's what I've read, but never verified so I could be wrong.

If you're really set on lowering your PH go with the driftwood, or even peat. Supposedly peat makes a great substrate for plants but again, I haven't verified that because the one time we tried to do it we did it all wrong and ended up having to empty out our tank to get rid of all the stray bits of peat.

And as for your plants, we bought some from our LFS and they were looking kinda sad but we brought them home, planted them in the tank and started dosing with Flourish and Flourish Excel and they're really perking up nicely.

 

[JG]

Hi There - Pardon the intrusion - I usually am in the saltwater forum - but occassionally snoop around here as I have a freshwater tank as well.

May I ask what sort of test you are running for your pH? I am a high school science teacher ( chemistry, physics, geology ...) and know that not all test kits are terribly accurate. For instance if you are using the paper test strips, they usually have multiple indicators in the paper and they can be quite a bit of "play" in thair color range. For many, the difference in colors from a #.1 to #.5 can be very subtle and quite open to interpretation.

 

[rubysoho]

actually, i am using the $5 drop kit... it is just called "freshwater pH test kit" but i've gotten the same reading at my LFS who uses the more expensive stuff since they get it wholesale. i think i am going to go with the drift wood... maybe i'll look into peat, but i think i'll end up chucking the plastic stump for the driftwood. i was looking at drift wood the other day... i didn't realize it was so expensive. the smallest pieces (about 8 inches long, no more than 2 inches in width) was $15 8O