Do large water changes change Ph?

[guppygirl123]

Two of my guppies died the other day. *cry* *cry*
Anyways I did a 6 gallon water change with dechlorinated tap water, like always. Only normally I do 3 gallon water changes every 3 days.... So my water looked good, tank was looking good, and I bought two new baby guppies. The next day one was dead. The people at petco tested my water and told me my Ph was 8.4!
I know it hadn't been that high before... So did the 20% water change cause my problem? I already got the Ph back down but I'm just wondering...

[Marinemom]

What is the normal PH in your tank? It is much better to have a stable PH then one that fluctuates up and down which can cause problems for the fish. What was the PH before the water change and what was the PH after the water change? Is there a big difference? Did you test the PH out of the tap? That may be your problem. Please do not use chemicals to adjust your PH because in the end this causes more problems then it solves. You can work with the PH that you have, you just have to make sure that it stays consistent between the tank water and the water that you use to do your water changes with.

Marinemom

[plah831]

water changes can result in changes in pH if you haven't done one in a long time. The buildup of wastes will make your tank water more acidic. That said, sometimes tap water supplies will change something to their additives that will also result in pH changes. Since you seem to be on a very good water change schedule (50% every few days), perhaps it is the latter?

[guppygirl123]

My Ph had been fairly neutral.... Maybe 7.4-7.6ish.... Sorry I can't really remember the exact number. I know my tap water has a fairly high Ph but I hadn't done a water change too long ago so I don't think the water was very dirty.
I got some of those dissolving tablets and added one in. Water seems pretty good now and all the fish are fine. I'm just glad they survived the sudden change.

[plah831]

Please do not use chemicals to adjust your PH because in the end this causes more problems then it solves.
I second that advice! guppygirl, you probably want to test your tap water pH as Marinemom suggests, so you can get an idea of a "baseline" or control value.

[CaitxSith]

did he use strips?

because my petco uses strips to test water xD

So it wasn't really a surprise when he told me that my water conditions were fine lol.

[wataugachicken]

strips are crap. i've heard that the best way to test the ph of tap water is to let it sit out for a few hours or overnight, that allows all the dissolved gases (that are in there from pressure in the pipes, etc,) to evaporate out and give you a better reading.

how did you acclimate your fish before releasing them into the tank? they may have been shocked going from the petstore water to the ph in your water at the time.

don't use ph-changing chemicals. . . ph is measured on a logarithmic scale, so each .1 of change (i.e. 7.1 to 7.2) is ten times more acidic (or basic) than the last reading. using chemicals and making the ph go all over the place is worse than it being high or low. however, you may want to call your local water company and see if they changed anything recently in their processing. they may have added something or changed a procedure that affected your ph readings. that kind of thing has happened before, very unexpected.

[SirWired]

Two of my guppies died the other day. *cry* *cry*
Anyways I did a 6 gallon water change with dechlorinated tap water, like always. Only normally I do 3 gallon water changes every 3 days.... So my water looked good, tank was looking good, and I bought two new baby guppies. The next day one was dead. The people at petco tested my water and told me my Ph was 8.4!
I know it hadn't been that high before... So did the 20% water change cause my problem? I already got the Ph back down but I'm just wondering...

You say you already got the pH back down... HOW did you get it down?

SirWired

[wataugachicken]

I got some of those dissolving tablets and added one in. Water seems pretty good now and all the fish are fine. I'm just glad they survived the sudden change.

chems.

[ROLLIN]

Since you seem to be on a very good water change schedule (50% every few days), perhaps it is the latter?


She usually does 3 gallons every 3 days on a 29, not a 6 gallon. Just thought I would point that out. :)

[CaptnDan]

My Ph had been fairly neutral.... Maybe 7.4-7.6ish.... Just to point out... 7.0 is neutral, and 7.4 to 7.6 is 40 to 60 times as alkaline (basic).

And since it seems to be a requirement for sharing knowledge here lately, here's a reference:

http://ga.water.usgs.gov/edu/phdiagram.html

[plah831]

She usually does 3 gallons every 3 days on a 29, not a 6 gallon. Just thought I would point that out. :)
ahh, thank you! Missed that one. So that's about 10% every few days, or probably 20-30% total every week, right?

[CaptnDan]

That's how I read it Paula. Though I think rather than doing 10% twice a week, I'd go for 20% once a week.

Changing 10% twice is less effective, but if the tap water has a wildly different pH this would be the better way to go until something could be arranged to match the WC water to the tank water - without the use of snake-oil additives.

[Star_Rider]

Just an FYI,
doing a 10% water change every three days is not the same as doing a 30% water change once per week..weird I know but in reality it has to do with dillution etc.

also, test yout tap immediately and then test it a 12 hrs later then again 24 hrs later.


some municipalities add chemicals in the water to slow down pipe degredation. here, we have slightly acidic water so (seattle) adds stuff to make the water temporarily less acidic..seems that once out of the pipes the chemicals degrade and the water returns to the normal pH.

[plah831]

guppygirl, I also have a 29 gal on which I do 50% water changes all at once. Sometimes I'll even do that twice a week, depending on how motivated I am :) So large water changes in and of themselves don't normally change water chemistry, as long as you keep up with the tank maintenance. That way, you maintain tank conditions close to source conditions, minimizing any differences between the two that might result in shock.

My fish aren't bothered at all, and there is no change in pH. They're so used to it, they just hang out by the siphon like it's part of their habitat!

So perhaps it is something that the municipal water supply is doing? Or do y'all think the 3 gal at a time is not enough, leading to acidic waste buildup in her tank?

[CaptnDan]

some municipalities add chemicals in the water to slow down pipe degradation

Here's a bit of an idea what they do to water before it comes out of the tap...

http://www.lenntech.com/water-treatment-chemicals.htm

[TKOS]

PH is all fine and dandy but knowing kh and gh is almost more important. If the pH truely is over 8 and the kh is super low then it sounds like a big dosing of phosphates in the tap water. My pH is 7.4-7.6 and my kh is like 1 degree (super duper low). I did small changes each week and my ph slowly dropped off to nothing on my test kit (less than 6). If I don't do at least 20% a week then I am in trouble, but that still keeps me borderline and the chance of a crash is high.

It sounds like increased water change amounts is what is needed in this tank.

[jennfier]

My tap is 7, then 7.8 next day, 8.4 day 2(&beyond) after sitting out with or without dechlor, and that's without even using a bubbler to degas.

It's about the same in my tank with fish. With plants, excel and a new diy co2 (which isn't doing that hot right now) pH is still only 8.2. I don't want to use snake oil so I just sit here and tear my hair out and chew pumpkin seeds.

[plah831]

so I just sit here and tear my hair out and chew pumpkin seeds.
:D I know that first one all too well!

[PhaidOut]

I am new to this forum but not new to fish keeping and I don't want to come off the wrong way, but.... Everyone is talking about water and pH but not anything that seems at all relevant to me. Nobody is talking about Ammonia, Nitrate or Nitrite or really the apparent source, Petco, either. Everyone is also assuming city water. Is it city water? What is the source?

Your water change schedule sounds fine. What about temperature difference between the tank water and the water you added? You could have shocked guppies if it was too drastic. Doubtful to me though - fish are built to handle "slight" but rapid changes in water temps.

How long have you had them? How long has the tank been set up? How did you cycle the tank when it was set up? How much do you feed them? What do you feed? What else is in the tank? What is the source of these guppies and are they a "type"? Did you check Ammonia, Nitrate or Nitrite (FIRST thing to check)?

I am going to bet it has something to do with Ammonia, Nitrate or Nitrite.

Just some ramblings...

Number one: Know your fish. Guppies, especially MegaPetStore guppies, are actually pretty difficult to keep for inexperienced hobbyists. I keep and breed show guppies and other fish - mostly live bearers at the moment. I am going to climb on my tiny podium for a moment. IN GENERAL buying fish from MegaPetStore is a BAD idea. They are on central filtration and even though they claim to have the ultimate UV sterilizer and it kills all disease - don't believe it. Fish in one tank get the disease it will make its way to the rest of the tanks. EVERY place I know on central filtration has the most unhealthy fish period. Even local places running central filtration. Certain species of fish are also very weak - depends on the original source a lot of times. For example if they import from Asia, it is just bad bad news. The philosophy of a lot of Asian fish farms is that you raise them in a pharmaceutical soup and they live with good productivity. They are weak without much of an immune system though. I know a person in Hong Kong who knows some of these people. Their philosophy is this - "Why do I want a fish to live more then a couple weeks in someone's tank? That is bad for business." Guppies, Angelfish, Discus and some others are particularly bad. Most of the fish in the US come from Florida and other southern locations but some do come from Asia. It really depends on the store and/or distributor. In my experiences, Petco doesn't seem to be the worst of places to deal with. It depends on the particular store - that I can say for certain.

Number two: pH notes. Like everyone has said - don't use chemicals to alter your pH. It is a disaster waiting to happen. If you are keeping advanced wild caught or extremely sensitive fish the story may change. I would say "common" guppies are probably fine up to about a pH of 8.0. I am doubtful your pH was an 8.4 - that does not make a lot of sense to me.

Number three: Water chemistry - non-pH. Guppies can be highly sensitive to changes in water chemistry. I don't think it has anything to do with the water changes. More likely would be high Ammonia or Nitrate created by lots of waste in the tank. Those will kill a fish rapidly - especially something sensitive like guppies. Do you know how much to feed? Do you ever vacuum your gravel? Was the tank cycled well? Another thing to consider - but I am not really considering it - is how hard your water is (in fact forget I mentioned it.)

Number four: Tankmates. Most catfish don't make good tank mates and actually neither do platies. Guppies are good with non-nipping fish and other small non-aggressive fish. Leaves out most. The only things I have had good luck keeping with guppies are various plecos, small shrimp and that's really about it. A lot of tetras, barbs and rasboras are fin nippers which is not good. I in general have not kept these kinds of fish in quite a while.

Number five: Age. How old are they? Guppies have short life spans... Some are surprisingly short and when you buy them in MegaPetStore they are usually probably in the 4-6 months old range. Not likely they would die at the same time but you never know. It is amazing the variance in aging between my strains - I have a couple that they will last a couple years no problem if carefully kept and one that I would estimate to be in the 15 month range (kind of new strain for me).

I don't want to sound like I am lecturing, but I have done this for many years and I am a subscriber to the old school methods of Fish keeping and despise the monster pet stores methods and the distributors they deal with in general. It is not that I am not willing to try the new things. I have tried and continue to try "new" things I hear about (bottled bacteria for cycling a tank for example). But I keep going back to the old methods because they truly do work and work well. I am tempted to start my own advice site about topics in general on they hobby just because I see so much information on the internet and hear it in the stores that is simply not true or straight out lies.

[plah831]

that's one heck of a first post, Phaidout! Good one, and welcome to AC!

Yes, we usually ask for ammonia/nitrite/nitrate readings with every "problem" especially if the fish are doing poorly. But the poster only asked about pH shifts, so that is probably why everyone is responding only to that part.

[wataugachicken]

i think we assumed city water because she used dechlorinator.

[TKOS]

I'd still like to know the kh and gh. Ph of city water can mean nothing if it is all coming from phosphates.

[guppygirl123]

Sorry, don't know the kh.
All my other fish are fine... The guppies didn't die from the Ph change, just so you know. They died (I'm assuming it was old age, I bought them full grown and I've had them for a while, and they weren't sick) before the water change.
I bought distilled water from the store, dechlorinated it, did a 3 gallon water change, and the water got back down to its original Ph- about 7.4. So I guess something wierd is going on with my tap water. Also all of my other fish are just fine.

I have noticed that guppies are very fragile. I normally buy them from my LFS, not big chain stores like Petco. I rarely see guppies at Petco that aren't sick anymore. But the 2 that are still alive are very healthy, in fact one has lived through an ich infection that a few of its tankmates had and never got sick.

Normally I let the water I am going to do a change with sit for a few days before actually doing the water change. Maybe that made a difference?

[Squawkbert]

Distilled water does not require dechlorination.

[guppygirl123]

I know, LOL. :rolleyes: Found that out after I did the change.... :idea: