Planted tank pH and CO2 injection

Question
Hello, I'd like to get an additional opinion regarding a possible conversion for my new planted tank (now an infant 4 weeks old and counting).

Initially, my intent was to set-up a low tech, planted tank. However, after some due dilgence and after observing the plant's recent growth, I am strongly considering making the jump to a high light/CO2 injection aquarium due to existing pH and other considerations.

Here are the existing tank parameters:

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125 gallon planted aquarium
Fluval 405 filter: media includes prefilter, Clearmax resin, 2 trays of Biomax and polishing pad.

Temperature: 80-82 degrees
T5 GLO High intensity flourescent lighting, ~1.4 watts per gallon

Pangea Flatrock background
Decoration: Several small pieces of driftwood

pH: stable at 8.2 (more on this below......)
GH/KH: Extremely low... low buffering capacity!

Water changes: ~35% twice weekly with surface substrate vacuuming
Substrate: Flourite, 2.5-3 inches deep

Plant Nutrients: Flourish Excel, Flourish Nitrogen, Flourish Iron
(conservative dosing regimen still under investigation)
Plants: Assorted, including amazon sword, anubias nana, brazillian sword, green onion, micro sword, rotala, etc. All species subject to change
CO2 injection: None

Fish: 2 african cichlids, 2 yo-yo loaches (hitchhiked home with plant water!), pangasius catfish (7 inches), bichir polypterus (7 inches)
Diet: Red bloodworms- 2 cubes, once daily

Ammonia: Stable at 0 ppm for life of tank (thankfully, given the high pH)
Nitrite: Stable at 0 ppm for life of tank
Nitrate: 5-10 ppm
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I am experiencing consistent but moderate bacteria blooms consistent with new tank syndrome, and am beginning to see considerable growth of brown algae and green spot algae. I did not bleach the plants prior to tank insertion, and I have no doubt that much of the algae came home with the plants I purchased. Naturally, the goal is to optimize plant growth so additional micronutrients will not be available for the algae. However, I have serious doubts about being able to make that happen with such basic water. The pH is stable at 8.2 (identical to the water coming out of the tap) and it is extremely soft due to the home's water softener. RO is not a reasonable option given the water volumes involved. I have no other options for water source.

The fish are extremely comfortable but plant growth is only moderate; I probably have 4 ppm CO2 in the tank at best given the water's softness and the existing pH. I also know that consistently adding buffering agents to lower the pH is a losing battle.... my best option appears to be to inject CO2 and to help the plants while simultaneously enjoying the lowering effect on the pH. I suspect that carbon could be rate limiting in this set-up, and I suspect the plants would prefer more neutral water regardless.

Any red flags I have missed? Does CO2 really represent my best option at this point? I enjoy doing water changes but can not tolerate significant algae growth once the tank is properly balanced. If I proceed, I will likely select a fully automatic injection system with pH probe.

Thanks in advance for the reply.

Answer
Hello, thank you for your email!
I'm really sorry to turn this question down and not give the response you wanted. But I don't have much experience as far as c02 injection.

I recommend you go over to-
Aquaticplantresources.net and post this question on the forum just as you've written it here. There you will get good knowledgeable opinions from well-seasoned aquatic gardeners who can help you better than I can.

I hope all goes well!
Karen~