I've been aware for a long time that my water sources have a high PH reading. My well water is around 7.7 and my aquarium water varies between around 7.6 and 7.9.
For the last two days, I've been trying to gradually lower this PH to neutral. I'd like to go as far down as 6.5. I'd like to be able to maintain it on the slightly acidic side at around 6.6 to 6.9.
(PH scale image on left based on data from http://www.ec.gc.ca/acidrain/acidfact.html)
From previous experiments, I am aware that peat will reduce alkalinity. I don't mean PH. By alkalinity, I mean the KH or buffering capacity. For example, I poured about 8 gallons of well water into a plastic garbage can and introduced a pillow case filled with about 10 cups of Canadian peat. I let this water oxygenate with a couple of air stones and a powerful air pump for 8 days and measured the KH afterward. The KH had dropped from a very hard 25 dkh to 5 dkh. However, the PH remained high as usual. So this experiment didn't really reduce PH although I was using a color test kit at the time which reads a solid blue color above 7. So even if the PH had dropped somewhat, I would not have been able to see the difference. The problem with peat is that it also colors the water. It gives it a brownish tea tinge. I don't use it in my aquariums anymore because this staining affects light penetration.
Anyway, back to PH. So I purchased a small bottle of a product called PH Down by Aquarium Pharmaceuticals. This product contains Sulfuric acid. I started dosing my 10 gallon tank as directed. The Pinpoint PH monitor showed an initial drop of less than .1. I continued to dose for two days. I eventually lost count of the dosing. PH seemed to drop around .2 and then bounce back a bit. I finally got it down to 6.9 and stopped.
Every time I dosed, the water's buffering strength seemed to diminish. In other words, the PH values were not so quick to bounce back up. I decided to measure hardness to see if the GH and KH had dropped in the process. The initial KH was 6 dkh and after dosing with PH Down, the KH had dropped to 4 dkh. According to what I've read, this low alkalinity means little buffering which means it's easier to manipulate PH, which can also be dangerous for PH swings. At any rate, the experiment worked. The PH dropped and the water's ability to buffer also dropped. One significant side note is that the general hardness seems unaffected. It actually went up a bit from 8 dkh to 9 dkh. It's possible that fertilizers added yesterday affected GH but I didn't bother taking measurements before and after dosing fertilizers.
Here's the skinny on my PH experiments:
10 gallon aquarium
Initial PH 7.7
Final PH 6.9 after dosing with API's PH Down
Initial KH 6 dkh
Final KH 4 dkh after dosing with API's PH Down
I wanted to know what other hobbyists were saying about lowering PH. It looks like people have tried different things. Some suggested vinegar and some suggested peat. As I've already said, I don't like to use peat even though it does reduce alkalinity and thus helps in altering the PH. Some had suggested Reverse Osmosis water which is what I use to reduce hardness and remove other pollutants. My RO comes from a Kent Maxxima system. I find this machine to be extremely efficient. A very good investment.
I also read that some products use a phosphoric acid with can raise phosphate levels in the aquarium. This is a nasty side-effect. I don't know if PH down has this effect. The product says it contains sulfuric acid. I will test my water to see current phosphate levels. I noticed the appearance of algae on the front glass this morning. A small, subtle patch. This tank has NEVER had any algae.
This is not the end of my experiments. Following the successful lowering of PH in my 10 gallon tank, I wanted to know if I could control PH effectively during water changes. So my first idea was to see how pure RO water PH is affected by PH Down. I also took this opportunity to test out vinegar as a possible alternative.
Here are the experiments and results:
TEST #1: RO water and PH Down
1. 1 cup of RO water
2. Initial RO water PH value: 7.78
3. Added 5 drops of PH Down (Sulfuric acid)
4. Swirled the Pinpoint probe to mix the solution.
5. Final RO water PH value: 3.31
Remarks: The PH drop was instantaneous.
TEST 2: RO water and white vinegar
1. 1 cup of RO water
2. Initial RO water PH value: 6.27
3. Added 5 drops of vinegar.
4. Swirled the Pinpoint probe to mist the solution.
5. Final RO water PH value: 4.30
Remarks: So vinegar actually does affect the PH but it doesn't seem to be as effective as PH Down, and I don't know how it affects fish or water chemistry.
TEST 3: To see how much vinegar is needed to drop PH as far down as 5 drops of PH Down.
1. Added 10 more drops of vinegar to the current solution.
2. RO water PH value: 4.05
3. Added 60 more drops of vinegar
4. RO water PH value: 3.65
5. Added 5 drops of PH Down
6. Final RO PH value: 3.21
Remarks: Clearly, PH Down is far more effective than vinegar.
I re-did the first test after soaking the Pinpoint probe in the aquarium for five minutes to make sure and got the same results.
TEST 4: Re-do TEST 1
1. 1 cup of RO water
2. Initial RO water PH value: 7.5
3. Added 6 drops of PH Down (Sulfuric acid)
4. Swirled the Pinpoint probe to mix the solution.
5. Final RO water PH value: 3.18
I am convinced API's PH Down product works well to reduce PH. Now I need to find out if it affects phosphates. If so, it might cause algae to grow in my tanks. I also need to measure for a few more days to see if I can maintain slightly acidic water conditions because as far as I can read, most plants prefer this type of water for more effective growth. That's the goal after all.
Here are a few links regarding PH. I read these during my experimenting.
http://fins.actwin.com/mirror/begin-chem.html
http://fins.actwin.com/aquatic-plants/month.9505/msg00150.html
http://freshaquarium.about.com/cs/waterchemsitry/a/mathcph.htm
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