ph in a planted aquarium

Question
QUESTION: I have a 50 gallon freshwater planted aquarium with the usual type of fish, angels, scissor tails, cory cats, pleco, neons and couple of killies.
No matter how hard I try to keep the ph at a normal level it stays very low.  I do weekly gravel cleaning to the extent of removing about 5 gallons of water with the debris.  I replace it with water from my tap which is very low in ph but very treated with Bullseye.  I add ph up every couple of days and still the water I test is bright yellow which my testkit says is very acidic.
I have gravel substrate and three filters running, one canister, one 50 gallon waterfall type and one undergravel.
The fish seem to be ok.  I have occasional fish death but nothing really to speak of.  What should I do?
Thank you so much for a reply.

ANSWER: Ahhh yes the dreaded ph paramater, probably one of the hardest thing about keeping an aquarium and having to use ph up or ph down. In my experience using those chemicals just dont work and it makes it hard on the fish going through a dramatic ph change every day it might seem like to them, depending on how often you have to adjust your ph. Now when your saying it's low.. how low are you talking about. Most fish can adjust to most nuetral levels... over time, the problem becomes most apparant when you add new fish and it's just a sudden ph shock to them and they end up dying.

Like i said over time fish can adjust to ph and if your not having a tons of deaths that proves that whatever your ph is buffering to should be adaquete for the fish themselves but i know it's frustrating.

There are better ways out there to substain a better ph, i think one of the best ways is a substrate such as red sea florabase which is madeup of clay and it's mostly used for planted tanks but it actually buffers the water to a good ph range.

You have to remember the goal of a fishkeeper in regards to ph is to keep a constant and stable ph range, even if it's lower then the ideal level... lots of swings with ph range can be very dangerous for fish and will prove there death.

What you need to do is figure out a way to keep stable ph and how we are going to do that is by the addition of minerals into the aquarium which will buffer the aquarium and keep it at a optimal condition. The easiest way and far by the safest would be the addition of limestone of crushed coral. There phyical makeup is enough to buffer you tank and make the ph rise, you just gotta do it slowly. The addition of crushed coral overtime (little by little day by day) and keep monitoring the ph level until you find a optimum level will prove successfull and solve your problem with the addition of ph down.. which only solves your problem on a daily basis.

I was in my LFS and they were selling crushed coral and limestone rocks so that seems like it would be your best solution. Do some more research into what others try out aswell.

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---------- FOLLOW-UP ----------

QUESTION: Hello again.  If I add coral or limestone rocks, how will I be able to keep the calcium from affecting the hardness of the water.  It seems an iffy tradeoff.  If I'm mistaken, I'll be only to happy to be.  
Thanks again for your help....I really need it.

Answer
Exactly the point, KH GH AND PH are all intertwinced it's hard to change on paramter and keep the others in check which is why it's not advised to try to change one unless it's absolutely necessary.

I searched for a article for about 20 minutes trying to find it which explains everything perfectly that i refer to alot.

Check this out and it should help you out alot. When it comes to ph, kh, gh me myself is still learning with it alot. I am learning more on the side of ph and kh with co2 but it's all the same ... chemistry lol..

Here's the link hope it helps you:
http://faq.thekrib.com/begin-chem.html

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