Help! - Low Ph And Fish Deaths

[Matthanley14]

Hi, hopefully someone can give me a clue what's going with my tank as I'm at a bit of a loss. The short version of the sorry story is:

50cm cube tropical tank with 3 honey gouramis, 6 zebra danios, 2 male guppies, 6 cory's and a plec (not sure what type but a small variety with white / blue spot markings). The tank has live plants, standard pea gravel and mapei wood and has been running for about a year.

Over the last few weeks I have lost 2 honey gouramis and my plec and the guppies don't look too happy with ragged fins and bloated bellies. When I lost the first gourami I checked my water and found ammonia, nitrate and nitrite all at 0 but ph at 6.0 or lower (API master kit so this is as low as it goes). I figured the wood was lowering the ph as it's always given the water a brown tinge so I removed it and bought some lava rock to replace it.

I have been doing a 25% water change every couple of days to try and raise the ph back to 7 ish but it won't budge even after 2 weeks. My tap water is about 7.2 and doesn't change when stood overnight. I also have another small tank with a betta in and the ph of this sits at 7.2 - 7.4 so don't think the tap water is at fault. I treat it with API stress coat before adding to the tank.

The only difference I have noticed in the last few days has been a bit of ammonia appearing about 0.25ppm on the test kit and some patches of brown algae on the glass which I have never had before.

I am going to separate the guppies and treat them for fin rot but I'm not sure what else to do.

Any ideas would be much appreciated?

 

[BiggTexx]

Are you sure Nitrate is 0 ppm? in a mature cycled tank, you should have some sort of a reading on nitrate at least. Are you sure to follow the direction on the test kit? Some test require two bottles to be used, and some need to be shaken hard for about a minute to thoroughly mix the solution before adding to the test tubes.

 

[NickAu]

When using API test kits I have found, That you must shake the bottles well then after you add the solution to the test tubes leave them sit for a few minutes, Go make a cup of coffee, Come back and look at the colour. 

 

[eaglesaquarium]

When using API test kits I have found, That you must shake the bottles well then after you add the solution to the test tubes leave them sit for a few minutes, Go make a cup of coffee, Come back and look at the colour.

The API directions clearly state to wait 5 minutes before taking the reading, as it does for both nitrite and ammonia. The pH goes much faster.

 

[Matthanley14]

I followed the instructions to the letter especially the nitrate test. I'll give them another go in a minute. Could the low ph be affecting the other readings?

I have also tried an old King British strip type test I had lying around and that gave slightly different results:
Ph <6.4
KH 50 mg/l
GH between 50 and 125 mg/l
Nitrate maybe 10mg/l it's hard to tell the colour difference
Nitrite 0

Will report back with the second API tests shortly........

 

[Matthanley14]

My second round of tests have come back with very similar results:

Ammonia 0.25
Nitrite 0
Nitrate between 0 and 5.0 it's only very slightly orange.

I have made sure to give the Nitrate a very good shake up as per instructions.

 

[Byron]

Low pH can affect some fish species, but the gourami are not ones likely, but then we don't know just how low it fell.  And of course, "low" pH is a subjective term; I have tanks that are well below pH 5.0 and the fish are thriving and spawning.
 
When assessing pH, you must also consider the GH and KH.  These are connected, and the pH is relative, generally speaking.  But the KH in particular, which stands for carbonate hardness or Alkalinity, works to "buffer" the pH, preventing it from fluctuating.  The higher the KH, the more stable will be the pH and less likely to lower.  You give the KH as 50 mg/l (= 50 ppm, which is roughly 2.7 or almost 3 dKH) which is low, and not likely to maintain the pH as I'll next explain.
 
The natural accumulation of organics in an aquarium will tend to lower the pH.  Organics include fish excrement, any dead fish, invertebrate or plant matter, decaying wood, and uneaten fish foods.  These accumulate mainly in the substrate, but also in the filter.  Various bacteria break them down (and here we are dealing with different bacteria than the common nitrifying species), and as this decomposition occurs, CO2 is being produced, and this creates carbonic acid in the water, so the pH lowers.  There is nothing "bad" about this, it is perfectly normal and in fact necessary, but it can be in excess and that is when trouble starts, at least for some (but not all) fish species.
 
Regular partial water changes of 50-60% weekly will usually maintain a stability.  Vacuuming the substrate to remove excess organics during the water change is important.  You don't want to go overboard, as some of this is good.  High organics can also occur due to overstocking and overfeeding.  Live plants help because they use up most of the CO2 being produced, though this cannot be pushed overboard either.
 
Last comment...I tried to explain the pH issue and what you are seeing, but I am not suggesting this is the cause of fish deaths, though from the information provided it might be.  How are the plants growing?  This can sometimes be a clue in this too.
 
Edit:  You posted the last test results as I was typing, and nitrate is 0 to 5, which is fine and again normal.  My tanks run around this and have for years.  Your plants are dealing with nitrate, not by taking up nitrate but by taking up ammonia/ammonium faster than the bacteria.  And in this lower pH, ammonium is prevalent, which is good.
 
Byron.

 

[Matthanley14]

The plants seem to be doing well, I have ended up with only 1 type left although I'm not too sure what it is as the "free" snails I got with some of the plants did a pretty good job of eating the rest. Hopefully there will be a photo of the tank in this post if I've done it right.......

I believe I live in a soft water area so presume this matches with the low KH? What is my best course of action regards this? I have been doing some research tonight and have seen crushed coral mentioned a few times to raise KH.

Thanks for the info so far.

 

[Byron]

That is quite nice.  I know some might think perhaps rather spartan with only two or three elements, but pulling this off is not easy.  Is that a Ceratopteris plant?  At first I thought it was Wisteria (Hygrophila difformis) but the leaf structure is different.
 
Before going down the "buffering" road, I would examine everything.  First, your water.  The GH at 50-125 ppm is very soft, and the KH is low too.  I would confirm these numbers (since you used an old strip test) with your municipal water authority; they probably have a website with data, or you can call them.  Also, confirm the pH value and find out if they add anything to raise the pH, as this can make a big difference [I have this].  As I explained previously, a low mineral content will allow the pH to lower more readily, but this is not necessarily a bad thing.  I have even softer water, near zero GH and KH, and I do not buffer anything; the plant fertilizers and substantial water changes weekly (my tap is 7.0 to 7.2) create a stability, and each tank is a bit different according to the wood, plants, leaves, fish and additives for the plants.
 
I have experimented with crushed coral, as well as dolomite and aragonite.  The latter two are better buffers because they will impact all three factors (GH, KH, pH) better, at least in my experience and from what I've read.  And it doesn't take much.  A small nylon bag of one of these in the filter will do it.  But with your low KH this can be a rapid and significant increase that may cause more harm than good, so it has to be done slowly.
 
What substrate do you have?  You mentioned corys initially, which would be best over sand.  Any thoughts on changing it out?
 
Byron.

 

[Akasha72]

it sounds like you've got the same problems as me with your water. Mine is incredibly soft with a Kh of 2 from the tap but it falls to 1 in the tank meaning that my pH runs at about 6. I've dealt with the issue by stocking the tank with soft water loving fish (apart from the SAE's, they are there to do the job of eating black beard algae) 
Your guppies are going to struggle in soft water as they are hard water loving fish. You are forcing them to adapt to something they're not designed for. I've had guppies myself - long before I learned about pH values and what fish like what. They only lived about 18 months and I believe that was because I forced them to live in soft water. We live and learn though.
 
The good news is cories love soft water, but they also love sand as a substrate so maybe consider changing that. Even on a soft pea gravel your not seeing the best from them. On a rough gravel they'd have lost their barbels which then makes is harder for them to feed.
 
As for the swollen bellies - it could be worms which has nothing to do with your soft water.
 
I'll leave you in Byron's capable hands though as he's really good at this. I just wanted you to know you are not alone

 

[Matthanley14]

Thanks Byron,

Just checked with the supply company and they list the Total hardness as 3.150 Clarke or 18 mg/l and very soft. Not sure why but they don't list the PH on their web site.

It would appear this is the root of my issue then? Still a bit confused as to why this tank has suffered but my small Betta tank hasn't.

The sand substrate for cories is something else I wasn't aware of. I thought gravel was fine so long as it was smooth.

 

[Akasha72]

the strange thing is I used to run two tanks. One large tank and one smaller one. The large tank had sand substrate but the small tank had pea gravel. The large tank runs at pH6 but the small tank never fell below 7!! I always blamed the substrate but that's now been disproved.
 
There doesn't seem to be an easy answer as to why this happened - both for me and now for you. It's all very confusing

 

[Byron]

Thanks Byron,

Just checked with the supply company and they list the Total hardness as 3.150 Clarke or 18 mg/l and very soft. Not sure why but they don't list the PH on their web site.

It would appear this is the root of my issue then? Still a bit confused as to why this tank has suffered but my small Betta tank hasn't.

The sand substrate for cories is something else I wasn't aware of. I thought gravel was fine so long as it was smooth.

 
As I mentioned previously, each tank can react differently, as there are several factors involved.
 
As to the low pH being the cause of fish deaths...I have never had this occur, but it certainly could.  We need to know just how low the pH is, and of course most hobby test kits only go down to 6 and a few will go to 5.  A pH of 5 will not harm very soft water fish.  But if the pH is dropping lower, say to 3, some species will be affected.  I would do some major water changes, with a thorough vacuum of the substrate in open areas only, and monitor the pH.
 
I kept corys for many years over a fine smooth gravel, but then I learned that sand was preferred and I am now glad I made the effort to change to sand in the six tanks.  I prefer it as a substrate ikn its own right, but there is little doubt that my corys and loaches appreciate this too.
 
Corys naturally sift through the substrate looking for food.  They are always found over a substrate either of mud or sand, or a mix of both.  They take in a mouthful, filter out any tiny creatures/food they find, and expel the sand out through the gill slits.  They can't do this with gravel.  Another issue with larger gravel is that bits of food get lodged down in it, and take longer to break down than what occurs in finer substrates like sand.
 
Byron.

 

[Akasha72]

jbl do a pH test kit that goes from 3 - 10
 
http/www.charterhouse-aquatics.co.uk/jbl-100-test-set-p-3154.html?osCsid=92eb8f326bb72292b6ebc0349873c110
 
I have this one and it's okay 

 

[TwoTankAmin]

Your tap has soft water with a pretty low KH. Not only will co2 create acidity, but so too does the cycle itself. The bigger one's fish load /litre, the greater the potential for pH to drop.  Weekly 50% water changes always help. I think your problem must be, at least to some extent, related to the low KH. I consider my water to be on the high end of soft and it has a KH of at least 75 ppm (1 ppm and 1 mg/l are about equal).
 
I have used crushed coral in a bag in my filter. For a 50 gal. tank I had about 1/2-3/4 cup of coral. I would not worry a ton about it acting too rapidly since is must dissolve to help and it does so slowly. It took me over a week to see changes on my test kit. In your case I would start with about 1/4 cup (using the type of measuring cup in the states which has both ML and oz scaling). If this isn't starting help in a week or two, add a bit more to the bag. Do monitor the params after you add it. My experience was I saw a rise in KH, but no rise in pH or GH to speak of. However, I was using it in a high tech planted tank which had injected co2 gas. Bear in mind the greater the fish load per gal or litre, the more/faster a tank can potentially drop the pH. Also, the more acid the water, the faster it can dissolve crushed coral, limestone etc.
 
I have also used crushed coral as an aid to creating dry seasons for spawning seasonal fish. I had to pre-treat the changing water to raise all the params some. My first step was to fill a 20 gal. can and then fill the carbon basket in a H.O.T. Magnum (it held about 2 cups of coral) and run it on the can for 18 -24 hours. The next day befor adding the other things I used I would test the water and see only a 20 ppm rise in TDS (1 dg of GH or of KH = about 17.8 ppm or mg/l). So, I would not worry about the GH rising too fast. But test anyway. Better safe than sorry