Water Dunderhead Ph Problem

[Sysiphus]

Hard to know where to start this tale - so here is the basic tank setup:

Setup on 11/4/06, 90 gal, 78 degrees, Corallife 65 watt 4 light 6K range on 10 hours a day 2.8 watts /gal, Pressurized C02 on pH Auto-Regulator 7.0 25 ppm C02, Rio reactor, 11 degrees hardness, 120 ppm Alkalinity, Fluval 405 Canister...

Balansae, Wendtii “Redâ€￾, Dwarf Subulata, Tall Subulata, Corkscrew Val, Anubias Petite, Anubias Barteri, Hairgrass, Java Moss, Wisteria, Lobelia small form...

2 - 4" upside down cats, 5 - 3" glass cats, 1 - chocolate Pleco, 1 - L146 Rubber Pleco, 2 - 4" Silver Dollars YIKES, 2 - Rummy Nose Tetra, 8 Neons...

Run 2 airstones at night don’t cut off C02 and 8 LED light blue night light.

****************** Here is what is happening

No significant problems except for the last two months. I change 15% water 2X’s a week. Change water is both aged (3-4 days) and declor treated. Here is the problem:

Within 5 hours after a water change the pH begins to drop from 7.0 until it gets to about 6.5 - water goes cloudy and fish all show stress signs. Took a reading of water chem during the problem time and it is:

pH 6.5 <<<
Alkalinity 40 <<<
Hardness 50
NitrIte 0
NitrAte 40

Took a reading of my change water (after it has sat for 3 days and been declor treated):

pH 6.8
Alkalinity 130
Hardness 0 <<<<
NitrIte 0
NitrAte 0

Just as a base - water test right from the tap (cholorine can sometimes mess with the results but I think these are on the mark):

pH 7.3
Alkalinity 130
Hardness 0
NitrIte 0
NitrAte 0

My plan is to increase alkalinity by adding crushed coral to the filter media. This should also bring up the hardness?

I did not mention but the water stabilizes at pH 7.0 after about 48 hours and water returns to perfectly clear. What I am assuming is that over time since the setup, the C02 has eaten all the buffering ability out of the water which accounts for good tank/bad tank syndrom I now experience.

As a stop gap to my runaway pH I am using Seachem PH 7.0 Liquid Neutral Regulator and that does bring the pH up but during the first 48 hours the pH bounces.

 

[WILDER]

I would do this thread in chat will get more replys.
Good luck.

 

[rdd1952]

There are couple things that don't seem quite right. Your tank appears to me to be lightly stocked unless the plecos are big. I wouldn't expect the nitrates to be that high since you're doing 2 water changes a week. Also, there is really no reason why the pH would drop lower than the pH of the water already in the tank and the new water.

First, is there any particular reason you're letting the water sit for 3-4 days before a water change? I can't see any useful purpose that serves since you are using dechlorinator. It could actually be bad since there will be evaporation during that time. Only water evaporates, leaving all the impurities behind. So in actuality, the water is actually worse when you add it to the tank than when it came from the tap.

I assume the reason the pH drops while just sitting in the bucket is that oxygen is leaving the water so as the oxygen leaves, the pH drops. I've never tried that but will test a bucket this week. Do you add the dechlorinator as soon as you run the bucket or just before you add it to the tank? Also, why are you doing 2 water changes a week? As I mentioned, your tank appears to be lightly stocked, certainly not oerstocked. Simply changing to one WC a week would eliminate half the stress on your fish.

It also makes no sense that the pH takes the big drop for a couple days and then comes back up. I am almost inclined to believe there is something in the buckets that is causing the problems. Have they ever had soap in them? There is really no reason the water should go cloudy after a water change.

Last but not least, I would stay away from the pH adjusters. They are keeping your pH in a constant swing. I think it is actually part of your problem. Besides that, most all of the fish you have would prefer the 6.5 pH to 7.0. For most of them, 7.0 is the top end of their optimal pH scale.

 

[Sysiphus]

Gonna move this to general chat as suggested but wanted to thank you for your thoughtful reply and answer a couple of questions that you posed.

The tank is lightly stocked and both plecos are the smaller ones full grown at 4†(which is bout where they are now). NitrAtes do stay between 20 and 40 consistently and is pretty certainly a result of the fertilizers put in the tank for the plants. I can stop ferts (which I have done) and test and the NitrAtes will drop below 10ppm in a matter of hours.

The water reserve does sit out primarily to bring it to room temperature. Here in Arizona the water coming out of the tap is cold and during summer the average temp in the tank is 79-81. The holding tanks (water bottles) are sealed so no evaporation and often I pre-dose replacement water with micro and macro ferterlizer/trace elements. As you can probably see from the original post the pH in the holder is 6.8 after 3 days and the pH right from the tap is 7.3. As to the cloudy water I have no clue but the water is perfectly clear until pH hits about 6.6 and then a haze develops until the pH again begins to drop after about 10 hours back to 6.9.

I can find no point at which I have a pH of less than 6.8 until about 4 hours after introducing change water to the tank. As you, I thought there must be something that has gotten in the water jugs or is being externally introduced and that is why I have worked quietly with this problem for almost 2 months before posting. There is just no contamination source.

I also really dislike any temporary chemical adjustments because it clearly is not a correction.

So here is where I am today… I have a working theory helped along by a LFS that I feel generally good about (not a “big box†fish shop).

Here is the working theory:

After 4-5 months of C02 introduction and with soft water going into tank the alkaline buffer has been complete exhausted. I am not sure I buy into this next part but I have nothing better – the LFS suggests that detritus are not decomposing well in the soft water and by using a product called “Liquid Gravel Vac†I can kick that into gear. The poor decomposition creates an acidic condition according to the LFS and when I do my water changes I “kick that up†and the pH is adversely affected. So keeping my personal need to only make modest changes in the tank, I have introduced two fist sized tufa rocks that should add some hardness to the water and a dose of the “Gravel Vac†(made by Tropical Science Labs in Phoenix, Arizona).

So I am taking Gravel Vac on faith and trying to address the one test result I believe I must correct by improving the low alkaline base.

The pH has been a steady 6.9 and I have not yet taken alkaline readings since I just introduced the tufa rocks 10 hours ago. At this time tank conditions seem excellent. Next water change on Sunday will tell a big tale.

 

[rdd1952]

I will check out the other thread. One thing to be aware of (and you probably already know it) with the Gravel Vac is that the bacteria that break down debris consume a lot of oxygen. If the chemical gives it a big kick, it could possibly produce a short-term lack of oxygen in the tank, especially with CO2 injection.

As for the temperature, I simply mix hot and cold water when I do water changes to get the proper temperature. I just let the water run for 30 seconds to a minute before I start adding to the tank with my python. It actually takes me about that long to get the temperature adjusted to where I want it anyway. Knock on wood, I've had 2 tanks running for over 2 years each with absolutely no problems at all.

What type dechlorinator are you using? I wonder if it is having some type chemical reaction with the ferts you use or if the ferts you are predosing with are causing the problem.

 

[Sysiphus]

Using API Tap Water Conditioner - tried to avoid all those that remove ammonia and so forth... I use PMDD from Greg Watson - plus a good deal of potassum Macro seems to be required for my tank.