Found out why my platies died...

[Undawada]

I've been bad... since my tank finished cycling three months ago I haven't been checking my water parameters.

I just had some platies die from ich so I checked my PH, Ammonia, Nitrites and Nitrates.

My Ammonia and Nitrites were 0ppm
My Nitrates were 35ppm
my Ph is 5.0

that seems fairly normal, except the last time I measured my PH (in august), it was 7.5 !!!!

I have no idea what caused the drop... it could have been gradual or sudden.

I havent made any drastic changes to my tank, except I added a terra cotta pot about a month ago.

Anyone have any ideas?

 

[lizard]

First thing - how old is your test kit? I'd try running the test again and/or taking a water sample to your lfs and asking them to do a pH test.

Nitrates seem like they might be a little high, but I don't know for sure.

Back to the pH - do you have any sort of rocks in your tank (other than gravel/sand), peat, driftwood, bogwood? The terra cotta pot shouldn't cause your pH to drop.

Good luck.

Pamela
aka Married Lizard

 

[Undawada]

Ty for responding so quickly.

I have two test kits, a mid range ( 6.2 - 7.4 ) and a wide range ( 4.5 - 9.0 )... both were purchased about 6 months ago.

The mid range was off the scale on the low end so it seems to confirm the wide range test kit's reading of 5.0.

Other than gravel I have a large slab of petrified wood, three small pieces of driftwood a terra cotta pot, three pieces of obsidian and live plants.

 

[yhbae]

Most likely it is those driftwoods that are causing the pH drop. Most wood leeches tannin which does exactly what you saw in your tank.

Did you treat those wood before introducing them into your tank? (i.e. boiling or submerging under water for a week or two at least) Is your water slightly brown by any chance?

 

[lizard]

You're welcome.

Hmmm...I think a post by CFC awhile back said test kits should ideally be replaced every three months, or some similar short period of time I'd agree that if the one seemed to suggest it was low, that it's likely that the other one is correct.

I'm not sure if the obsidian or petrified wood will change the tank pH. Perhaps someone else can answer that question. I don't think driftwood will change the pH, but that could depend on the kind of driftwood - a driftwood expert I am not!

Do you have CO2 in your tank? What's the pH of your tapwater? How often do you do water changes and how much?

Hmmmm....

Pamela
aka Married Lizard

 

[Undawada]

No, the water has always been clear.

I added the wood during my tank cycle, when I was monitoring PH and other params religiously... could it have been a delayed reaction of a few months?

I never boiled the wood, but it was sold as "pre-treated".

 

[yhbae]

Hmm... So may be it isn't wood. I doubt his setup will allow that much concentration of dessolved CO2 to get to that level of pH...

Of course, this is all assuming your tap pH is 7.5. Is this the case?

 

[Undawada]

PH of tap water is 7.0, no C02, I do weekly water changes of 6 gal.

 

[lizard]

I would think that doing water changes of that size every week would keep the pH from getting so low... Maybe not, though... I seem to recall that tapwater pH can vary day-to-day, but it shouldn't be a large variation.

Yes, I think the pH change would be a slow one. If it was a quick one, the fish most likely would have died, or gotten quite sick from it. If it's changed slowly, they've had time to adjust to it. Have you added any new fish recently?

Faulty/expired test(s) is still the only other thing I can think of, if it's not the wood or rock...

Pamela
aka Married Lizard

 

[Undawada]

No new fish, but I did have a bunch of fish die suddenly. I lost one oto and a few platies within a week or so from ich (could be caused by stress from dropping PH). My emerald cories are OK but they tolerate lower PH better than platies or otos as far as I know.

My first reaction is to buy some crushed coral and add it to my filter to raise the PH, but Im worried about whats causing the change in the first place. If the problem resolves itself, my PH will then be to high. It could also be causing other, more subtle changes.

 

[yhbae]

Perhaps you could do a simple experiement. Get a bucket of tap water. Measure pH. Take ALL of your wood out of your aquarium, and place them into the bucket. Let them sit for one day, and measure pH again. (All tannin must have been leeched out in your aquarium by now, but you never know...)

As lizard mentioned, given your water change volume, there's no way this pH change would have been gradual. Either your test kit is seriously out of wack, or you have something in your tank that is capable of affecting pH in a relatively short period of time (days).

Also, what is your KH value?

 

[Undawada]

Dont have a KH kit.

I will probably do your experiment idea within the next few days as I'm switching to sand and will be removing all my wood anyway.

 

[CFC]

I think yhbae is on the right track here, if the KH of your water is low then it affects the buffering capacity of the water and allows the humic acids released from the bogwood to lower the pH, any decaying organic matter in the tank such as uneaten food, fish poo and dead plants trapped in the substrate will add to this. This is known as pH crash and can happen very suddenly as the ions which buffer the water and keep the pH stable are used up and not enough are replaced via water changes to meet demand.

Either buy a KH test kit or ask your lfs to test it for you (if they will) and let us know the results.

 

[Undawada]

I will...

should I move the fish to my 10 gallon hospital in the meantime?

I have 3 emerald cories (about 2") two otos (about 1") and two platies left, one adult and one juvenile

 

[CFC]

I wouldnt move the fish to a tank with a higher pH as they may go into pH shock from the sudden change, if you are going to ove them you will need to acclimatise them over several hours using the drip method.. The Brochis (emerald corys) and otto's should actually be enjoying the lower pH, only the platties which come from habitats with hard alkeline water will be uncomfortable.