Need Help: Low Kh/gh, Very High Ph

AstroTrev

Member
Hello everyone. I'm hoping some of the folks with lots of experience in water chemistry can give me a hand. I currently keep a 75 gallon planted freshwater aquarium stocked with (3) bolivian and (3) blue rams, (15-20) black phantom tetras, (12 but decreasing) cardinal tetras, a bristlenose and clown pleco, and some (6) otocinclus. About 3 days ago I found two dead cardinals stuck in the filter, but really thought nothing of it. These things happen from time to time. The following day I found 3 more, and today I found 2 more, at which point I realized something strange must be going on. I followed up with a water test and was surprised by the results. I will try and describe my setup and water test results as succinctly as possible.

Ammonia: 0, pH: 8.2, Nitrite: 0, Nitrate: 0, DKH: 4, DGH: 6, Water temp: 80-82 degrees F
Substrate: 100% Seachem Flourite
Assorted freshwater plants, real driftwood (on large piece anchored with slate tile)
I use 100% RO/DI water that I buffer with 2.5g Seachem Alkaline Buffer and 1.9g Seachem Acid Buffer per 5 gallons water, and 16g Seachem Equilibrium per 20 gallons water. Lately I have been doing 25-30% water changes weekly. Daily I add a cap and a half of Seachem Flourish Excel, and every other week I add half a capful of Seachem Flourish. I have 4 AquaRay Grobeam Ultima 600 LED bars and a Satellite LED bar.
AquaClear 110 filter loaded with assortment of sponges/floss, felt-type filter media, ceramic pellets, and Seachem Purigen.

These water test results have been pretty stable, with exception to the pH rating, which is usually in the low/mid 7.0 range. I believe it is this spike in ph to 8.2 that is killing my fish, because all of my other conditions have been relatively stable (besides the recent addition of some more driftwood).

I have been trying to get my water to stay acidic for over a year now, and was really hoping that using RO/DI water along with real driftwood would do the trick. Somehow, my water always seems to get more basic even while maintaining low KH and GH. Can anybody provide some insight as to why I might be experiencing this low KH/GH, very high PH condition, as well as any suggestions to help? I've done a lot of reading on the subject and like to think that I have a pretty decent understanding of it, but perhaps I am missing something. At the end of the day, I really just want my fish to stop dying!
 

Jo3y

Member
AstroTrev said:
(besides the recent addition of some more driftwood).
!
It seems that your tank has been running smooth for quite a while, then you suddenly add another piece of driftwood (yah, I know, an innocent piece of driftwood lol) & then you start having issues... I would start by removing that piece & do another water change? I'm not a big expert but sometimes its the little things... It seems like you are doing great besides that don't you think?
 
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AstroTrev

Member
I was thinking the same thing. It would be really disappointing if that were the case, because it is a $70 showpiece sized driftwood. I'm also wondering if it could be the slate tile that is weighing the driftwood down, but I've been using similar slate tile in other aquariums for a long time without any problems.
 

ChrisX

Member
My guess is that your KH is low enough that large pH swing is a probability. I also use Alkaline buffer to bring KH up. I have heard that the target is five, to avoid unexpected ph swings.

Also I'm not sure how the alkaline and acid buffer work together. Its possible that some condition in the tank changed that interfered with how these work. It may also be that by replacing evaporated water, these products stay in the tank and change your parameters over time.

Not a chemist, but I'm sure one will chime in shortly.
 

Zahc

Member
My water is similar to yours actually. Off tap my pH is 7.8 and hardness is 3DKH and 4DGH. I'm still not sure how or why my water measures that way, but I just use regular water changes as my pH stabiliser. Most fish can happily adapt to a pH of 8.2 aslong as it remains stable.

With low KH your pH can drop very quickly. So for me I just make sure I change 50%+ every 4-5 days. My water is very stable (pH is a constant 7.8), and very soft which is what I'm after. It seems a lot easier than adding buffers every water change, and half of them don't work safely anyway, usually rising again causing more pH shock.

Driftwood leaching tannins will drop your pH aswell. Boil it for 30 minutes and it should reduce the tannins and reduce pH drop.
 

CindiL

Member
Hi, your GH is fine for your fish that you have and your KH is borderline low. Above 5 would be more ideal. I think the issue you might be running into (assuming its not disease) is when you mix acid and alkaline buffer you are probably dropping your ph during water changes and then it bounces back up because the water will revert to its "natural" ph state. Even RO water, depending on its source can have a higher ph. Mine for instance has a PH of about 7.9-8.0 once aerated (due to CO2 in my well water).

I think its better to just use alkaline buffer which will put it at where you're at now most likely and you'll avoid ph swings. Also, if you're starting out with a low KH like most RO water is, then the alkaline buffer increases KH but acid buffer lowers it, again which can lead to ph fluctuation.

We shouldn't rule out disease though with rapid deaths like that so a few questions:
1. Did you add any new fish in the last couple of weeks?
2. Do any of the fish go off by themselves at all before death?
3. Sit on the bottom or gasp at the top before death?
4. Any visible patches on their body or fins at all?
 

tjander

Member
I would put money on the PH swing killing your fish. Also don't think Slate would cause a ph change. Driftwood should only lower your ph..
I used to mix buffers to get the PH to a close match to my tank. This work well but was too much work. I since started slowly adjusting my tank ph to match my tap and just let it go with water changes. Used a little crushed coral to raise the KH and stopped the buffers altogether... good luck
 
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AstroTrev

Member
Thanks for all the responses everyone. I am going to do a water change today and I think I will increase the KH to 5dKH to try and stabilize any pH swings. I might also do more research into eliminating the acid buffer, because in most of the reading I've done it seems most folks using RO/DI water just use the alkaline buffer, which appears to mostly be baking soda.

As far as disease, I'm not ruling this out yet either. The cardinal tetra deaths seem to have stopped, and I never noticed any symptoms of disease in them; however, they are a delicate fish and it seems like it doesn't take much for them to go belly up. One of my blue rams started breathing rapidly and isolating itself, and I found it dead this morning, so I think sickness could be a real possibility. I've been building up schools of fish over time, and so have been making additions every few weeks. This could easily explain the deaths. I am just used to seeing some sort out external symptoms, ich, fungus, red spots, etc. so was surprised when the bodies seemed to show nothing.
 

ChrisX

Member
I'm sorry for your losses. Hopefully you can get it worked out. You have a challenging tank.
 

tjander

Member
Alkaline buffer from Seachem is more then just baking soda... baking soda will work but its effects don't last as long from what I have read resulting in either adding more or a ph crash. All I am saying if your going to use baking soda be careful and monitor your ph.
 

CindiL

Member
Baking soda has carbonates and bicarbonates both, where baking soda is just bicarbonates and doesn't seem to last as long. When I use alkaline buffer, I feel confident knowing my KH will not drop over a week in between water changes so I think its a worthwhile product. I think baking soda is great in a pinch though.

If you continue to see deaths with no causes then that will start pointing towards a bacterial infection going through the tank and you'll want to treat.
 
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AstroTrev

Member
HI everyone. First off, thanks for the help and pointers. I think increasing my KH by one degree will go a long way in helping control any pH fluctuations with minimal effect on my overall system. I've tested my water a few times over the past couple of days and it appears my pH is back down to its usual 7.6 range, which leads me to think I had some sort of major fluctuation going on for some reason. I will continue to monitor and adjust. I really appreciate everyone's assistance! Thank you so much.
 
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