TX Holey Rock and ph parameters - The Planted Tank Forum
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post #1 of 4 (permalink) Old 09-26-2017, 11:52 PM Thread Starter
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TX Holey Rock and ph parameters

I have a nicely established (4 months) that is heavily planted, it has 2 older (read at least 5 years old) tube style lights and an LED, the tank has water changes of 40% to 50% weekly. No CO2 (yet).

The rainwater is collected in 275 gallon IBC water totes. I tested the water at a local lab where I had worked at a few years ago and the ph was 4.6 (ouch) The water is pumped into the house and then filtered and heated to aquarium temp in a 35 gallon Brute trash can.

I had 8 guppies in the tank, 5 males and 3 females. One of the females has given me 4 youngsters that are happily swimming around like champions.

This is where the story goes sadly awry, first one of the females died. It happens no big deal. Then one by one all the adults apart from two males and the fry are all that is left.

After checking the water in the trash can from the vats and the ph was right at 7.0. Checked the aquarium and it is at 6.4-6.6. The only difference I have made is I placed a piece of TX holey rock into the trash can to bring up the ph (said he hopefully) three hours later as I said it is right at 7.0 and the tank is lower as per above.

Am I imagining things or is the piece of rock really going to make such a drastic change within three hours?

I am wanting to add some Corries and maybe a couple more female guppies but I do not want to have them die on me within 48 hours.

As far as I can see all the other parameters are within spec, suggestions are more than welcomed.



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Last edited by StevieD; 09-27-2017 at 09:43 AM. Reason: Grammar
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post #2 of 4 (permalink) Old 09-27-2017, 12:18 AM
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How much and how quick and if any change at all is something of a guess as rocks vary by nature. Texas holey rock is limestone and limestone does vary. So the answer will vary also. Some points that do matter are simple. the lower the PH at the start, the faster and larger the change. But a big item in how fast is the condition of the rock. If they are really porous type limestone, and holey can tend to be, the more the chemicals that make up the rock and the water are exposed, making it faster. Also if there is dust on the rock, it is more exposed and does work faster until the dust is done reacting.
So 6.4 is pretty acidic and if there were dust and the outside of the rock was porous, you can get a pretty big bump at first but it may level off and not be much to notice. As the PH gets closer to 7.8 things will level off. One of the reasons I like to suggest rock when people want to have higher PH is that it has a self limiting nature as it gets to a point that many fish like. Also the rock tends to add to the GH and KH so the buffering effect does tend to keep things more stable then some chemical treatments.
If rinsed to remove dust from being knocked around, I would not expect that much of a quick change. But then I started out with the idea that it is pretty much a "guessimate"?
Not sure that I would be sure of a connection between the rocks and fish death as dying seems to be pretty common when we start. Maybe , yes but also many other things that can go wrong to fake us out.
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post #3 of 4 (permalink) Old 09-27-2017, 05:04 AM
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Texas höley rock is primarily dolomite made up of calcium carbonate and magnesium carbonate. The Low PH of your rain water is mainly from CO2 each drop of rain absorbed as it fell out of the cloud. When dolomite comes in contact with the acidic water CO2 is released from the water and some of the rock dissolves. The rock will increase GH and KH. I don't know how much but with very acidic rain water it could be substantial. I would suggest getting a GH test kit to determine how hard it gets. In contrast the untreated rain water would be very soft with lo GH and probably no KH.

Guppies from my understanding prefer hard water instead of soft water. However they might not be able to handle a sudden increase when you did the water change and added the new water they would have to adjust to the sudden GH and KH change. Perhaps this change occurred to fast and too large for your fish to adapt. Perhaps you should have adjusted the fish to the dolomite exposed water by doing a number of small water changes over a week or two. Once the fish have adjusted to the new water. After you have adjusted the fish to the harder water you can go back to your weekly 40% to 50% water change.
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post #4 of 4 (permalink) Old 09-29-2017, 08:12 PM
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post was meant to be new post.

Last edited by PlantedRich; 09-29-2017 at 08:14 PM. Reason: remove
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