High Gh, low Kh: dead ram

[JdE]

Hi! I have a 30G low-tech planted aquarium with some chemistry problems. The water in my place has a high Gh (10-12) and thus a pH close to 8, but the Kh is low (1-2). After killing some tetras I started mixing RO water with tap water, but I can't figure out how to increase the Kh without going too high on the pH. Over the last 2 years I've tried baking soda, wonder shells, replenish, tap water with pH balancers and a combination of all of the above, but all it ends up doing is decimating my fish, the last one, a beatiful female ram I had for about 8 months. At one point my Gh was so low that I wiped off all snails and shrimp!

What am I missing?!

30 gallons, 8 rummy nose tetras, 2 rams, 1 gourami, 2 blue rainbows, 4 loaches, 4 amano shrimp, 3 ottocinclus, 1 thread finn, plenty of turbinate and apple snails.

pH 6.6, Gh 7-8, Kh 0, nitrates and nitrites 0, some algae grow, water change weekly with 8 gallons (6 RO, 2 tap water)

 

[rkilling1]

You have some mis-understandings in your post.

Here is a quick article on KH/GH/pH:

Water Hardness

Please read through it and I think that will help you out.

 

[aqua_chem]

I'm confused about what exactly you are trying to accomplish by tinkering with your GH/KH. Most fish can adapt to harder water. I've kept rams in GH 13/ KH 10 water without much issue (they even tried to breed a few times).

 

[CorallineAlgae]

So you're saying that the water from your tap has problematically low carbonate hardness? Are you getting big pH swings between before lights and after lights? If you have an unusual local water table, compared to other areas in the country, you may want to ask the LFS guys if they've had the same problems. Call em on the phone, a few places if you have more than one. Sounds like you've tried the most common approaches already. Though, using RO water isn't the best idea if you want a higher dKH. sounds odd that you would have very low carbonate hardness but a stable high pH. You should totally skip the RO IMO. Maybe I just need to think about your problem more. Something doesn't sound right. What substrate are you using?

 

[JdE]

Thank you for the replies. Yes, I think the problem is that the Gh of my water is 2 or 3 times higher than the Kh, but I can't find an effective way to fix it.

I have gone through many "cycles" in the last couple of years, in which I just get tired of keep trying to manage the water parameters and start to introduce straight dechlorinated tap water, but short and long term this killed rummy noses, thread finns and ottos. Then, when I measure the water parameters, the pH is above 8 and the Gh is high, but the kH does not rise above 2-3, so yes, I think that could be not buffering fluctuations in the pH, while Mg and Ca are probably increasing.

AT that point I go back to mixing RO with tap water, but in a few weeks the kH is so low that I think the tank goes back to the pH roller coaster and kills some fish (like the ram last week).

When I tried baking soda, a few times I measured the kH and pH right after mixing the water and 24 hours later, and both go back to the original value, so I think this is causing even worst fluctuations of the pH. Please do make me know if I'm confused about the relationship between these values.

The substrate I have is Fluorite red, from Seachem, and it is curious you brought that up, because I don't seem to have the same problem in other tanks with different substrates... How that works?

 

[Daxhua]

I don't think high GH / PH and low KH are the problem. I don't know how long you've had your fish but more than likely it's your fish supplier. Half of the fish you have are considered delicate fish and I've read most rams don't have a long life span (I may be totally wrong about that). As stated before most fish even delicate ones can adapt and do well with high GH, PH and low KH. My GH is in between is well above 15, KH is at 6, and PH was at 8 until recently when I added driftwood now it's 7.4. Right now I successfully keep neons, cardinals, and otos which are considered delicate fish and I've kept others at the same params.
I don't think wonder shells will do anything for your KH level but they will raise your GH level.
IMO unless you have a good understanding of chemistry, are willing to experiment with your tank and possibly suffer a few loses I wouldn't mess with RO water for a freshwater tank. That's just me.
Your water supply is low in KH so your looking at constant testing and adding a KH buffer with every water change or as needed. Don't know if you've tried this but using peat moss or driftwood will gradually lower PH.
From my personal experience from the time that I really started messing too much with my tank's parameters such as GH, KH, and PH to when I finally stopped and just let my tank be is when my tank was the most problematic.

 

[CorallineAlgae]

I agree that mixing in adjustments usually causes more problems than it solves. Having said that, most of us use something to amend our water, weather it's peat, driftwood, special substrates or crushed coral in the filter. I have terrible tap water and used RO with Equilibrium for years but found it's fine to just go with tap water or at most 1/2 RO and 1/2 tap. But by water has a very high KH.

Because you have a low KH a good idea would be to use straight tap water with dechlorinator and see if the KH in your tank builds up over time. This can happen when water evaporates and the minerals in the tank become slightly higher. Then you use tap to replace it. It very slightly higher again. Water changes keep the water from getting to hard. You could always try using a small bag of crushed coral in your filter. It's a gentler way of amending unstable low KH water. Just like using peat softens overly high water but reversed.

The poster above me has a point. The fish store may just have bad fish. If not, if their fish are good, you can bet that they keep them alive in straight tap water and not RO.

 

[JdE]

Fish are fine, they come from 3 different providers and spent 4 weeks a tthe hospital tank before going into the display tank and I'm able to keep the healthy for a while. This is not something new, I think my main question is if there is a way to increase the Kh without introducing more hard minerals (Ca). I do have drift wood and all other parameters are good for the species I have, but I would like to have more buffer capacity. I will try to mix more tap water, but the hardness in this water changes a lot from week to week, so it's easy to forget to check it and screw up

 

[CorallineAlgae]

This is something I've never heard of. Your tap water parameters change from week to week? And I thought my towns water system was bad. Still, your towns water must come from a single source. It's hard to imagine it can vary in any significant way over short amounts of time. Have you asked the local fish store guys, who have the same source water as you, what they recommend you do? Seriously, if you have a local water problem that wonky they're the guys that'll have the most experience dealing with it. Are you living in a mountainous area by any chance?
Just a thought, does your home have a water softener?

 

[JdE]

Well, this is Alabama, and the place where I live has a separate source of water, probably from a well. I was told once in a while they flush Magnesium down the system to "clean it up" and I suspect this is increasing the Gh without rising Kh. I have tried to use water from the city system, but it can also get too hard. I used to used the water from a water filter, but I read that it increases the sodium and lowers minerals in the water, so I stopped doing it.

 

[CorallineAlgae]

I thought it sounded like softened water was used at some point. How long ago did you stop using the filtered (softened) water? Man, you really do have odd water. I don't know what to say about the well water.

You may end up being one of the few people who may need to use RO water plus something like Equilibrium and an alkaline buffer. I did that for a few years. It works but it's not as easy as plain tap. I still think something sounds odd. Did you say that you have well water, softened water and city water?

 

[Daxhua]

Well, this is Alabama, and the place where I live has a separate source of water, probably from a well. I was told once in a while they flush Magnesium down the system to "clean it up" and I suspect this is increasing the Gh without rising Kh. I have tried to use water from the city system, but it can also get too hard. I used to used the water from a water filter, but I read that it increases the sodium and lowers minerals in the water, so I stopped doing it.

I think you have too many variables here. You can't control the city or well water but you can have some control over anything else thats put in your tank water. May I suggest that you stop using well water and go with city water your GH will be high but at least somewhat stable, then gradually stop using or lower the amount of RO water. I'm telling you fish can adapt and do well in hard water I'm not the only one who knows so. If your KH is really that low then you will have PH swings so your going to need to start adding an alkaline buffer. That is just my suggestion.
You're going to have to start doing research and studying on aquarium water chemistry if you decide to go with RO water, mineral replacement and buffers.

Quick question. Are you using a liquid test kit?