Tank Chemistry Not Making Sense

[SteamCarriage]

I can't figure this out. Here's the pure data. Any thoughts greatly appreciated.

I've had fresh and salt water tanks in the late 80s into the early 90s. Getting back into it. Have a 33-gallon fresh water planted aquarium going since mid-2011. Now want to start a seagrass & sea algae planted aquarium. The issue is with getting the salt aquarium pH & dKh values right.

30" x 12" x 18" glass aquarium is set up to become the seagrass planted aquarium (photo below). I may add some reef elements in the distant future. My plan is to get the tank set up with salt water and substrate and get the canister pump and powerhead running. Cycle ammonia, nitrite & nitrate. Then add some hearty salt water fish (1/2 dozen for the time being) and some live rock along with several species of hearty seagrass. Once that seems to be functioning fine I'll start adding select salt grasses and algae along with perhaps some invertebrae, sponges, etc. as the tank continues to progress.

For the record, I'm using API test kits. The numbers I'm providing are correct. I've verified the pH readings of the API kit by verifying the reference solution. I've also used pH test strips to get the same numbers as API. And I've had water to the LFS and had them test it only to come up with the SAME results. If you're thinking of suggesting the test kits are giving bogus numbers, then read no further. I've done pH and dKh tests with multiple kits including the LFS store and ALL readings are within 5% of each other. This problem is NOT the test kit or the testing process.

I used tap water run through an RO unit with carbon filter (no DI unit). Same water is used in the fresh water tank with no problems 2+ years later. pH is 5.5 and dKh is 1 both from the spigot and after running through the RO/charcoal filter.

The water had CaribSea Scientific Salt Mix added; made up as one-gallon lots. The salt level is 1.021 - 1.023 and the pH is now 8.3 with the dKh at 13 - 14 and the Calcium at 480 - 500. The salt water mix values I think are nominal before it was added to the tank in one-gallon increments.

The tank has about 5" of CaribSea substrates in preparation for the seagrasses which need a thick substrate. They are Dry Aragonite Special Grade Reef Sand - 15 LB; Arag-Alive Bahama Oolite sand - 20 LB; Dry Aragonite Super Reef sand - 40 LB; and Aragamax Grand Bahama Biome sand - 30 LBS. I have two sandstone rocks in the aquarium. These rocks were also in my salt water fish tank back in the 80s and 90s. I never had a pH problem back then with this rocks in the tank and I can't see them being a cause of my current low pH and high dKh problem.

Ammonia, nitrite, and nitrate are currently all 0 because there is nothing living in the tank. I plan on added some ammonia to the tank to start the cycles and have them stable before adding fish and plants.

Here is where the issue is. The pH of the water in the tank is now 7.4. The dKh is off the scale (I stopped at 25 drops or dKh at 25). The pH was 6.8 right after the water was added. The filter was started to clear the cloudyness. A powerhead was also added to stir the surface and tank water. I have let the aerator run on the powerhead but it doesn't seem to change values (i.e. the tank is a short distance from an open window so its not house CO2 causing the pH imbalance in my opinion and the CO2 injected planted aquarium is on the first floor at the other end of the house).

I've added 8.8 ounces of SeaChem Marine Buffer on recommendation of my LFS who I feel are quite experienced. They verified my 6.8 pH levels with their test kits and I've raised the pH with the Marine Buffer over a week. Its still obviously low. dKh is still way high (stopped at 25 drops). The Calcium level is fine - hasn't moved - 480-500.

There is obviously something with the chemistry that isn't right. I can't figure it out. I can't see it being CO2 since the tank is near a window that has been open due to the great weather we've been having lately. Only one person lives in the house and no other pets. The fresh water planted aquarium is CO2 injected however that is on a lower floor and opposite end of the house so I can't see it contributing.

I have a notion to continue adding Marine Buffer until I get a pH of 8-ish. My dKh will have to stay off the scale - perhaps due to all the substrate I have. Calcium seems to be holding fine.

I'm looking for comments and suggestions. As anyone experienced something similar and if yes how did you correct it? I'm baffled because the water numbers before being added to the tank are good, after addition to the tank they have changed and in a very wrong direction.

Photo of the tank is attached for reference. Thanks in advance for taking time to respond.

[disc1]

The alkalinity is sky high because of the buffer. That's all it adds. The pH effects are always temporary at best.

If you keep adding buffer and running alkalinity up just for the sake of pH, you will eventually end up with a snowstorm. You don't want that.

My advice would be to forget about the pH for a while. First of all you have nothing living in there and haven't done a cycle yet. So pH isn't going to be stable for a while anyway.

And secondly, pH is about the least important of all the parameters on a saltwater tank. Not like freshwater in that sense at all. Alkalinity is THE most important parameter in a slatwater tank. So why are you screwing up the most important thing chasing around the least important thing?

Get the rest of you water chemistry straight and get the tank going and THEN see where your pH comes out.

[disc1]

Originally Posted by SteamCarriage

The fresh water planted aquarium is CO2 injected however that is on a lower floor and opposite end of the house so I can't see it contributing.

CO2 is a gas. It will move very rapidly to fill whatever container it is in. Yes, the planted freshwater tanks will contribute to the CO2 load in your reef tank at the other end of the house.

[dppitone]

You're doing too much and writing too much. Just put everything in there to start the cycle and give it some flow. Check Ammonia, and/or nitrites, and/or nitrates twice a week and change water as nitrates spike. That's all you should do now. IMO do not do any of the other stuff. It's a marathon, not a sprint.

[thegrun]

At this point I wonder if you would be better off adding calcium to cause a snow storm and get some of the alkalinity out of the system. I agree with the above posts, don't worry about pH, but you are looking at a disaster with your alkalinity levels. I would start thinking about a 80%-100% water change rather than trying to get the current water chemistry back in line.