ph prob i cant shake

[MattG]

Gday there! I have 2 500lt tanks 1 fish tank 1 sump and 2 bath tubs as grow beds one has 16mm screening other has scoria. I only have 12 gold fish at moment want to get silver perch as soon as i feel i have some control over ph! I cant get it down from 7.8- 8.0! System been running for about 5 weeks, fish for about 3. Tried 200ml lemon juice daily for more then a week still getting 7.8 s. Tried turning of one grow bed for few days to see is rock was keeping it up,more lemon juice! nothing! Alternated bed same thing! nothing! I dont know what to do next, will it get better as system cycles.Would really appreciate any help.
Thanks Matt

[RupertofOZ]

If you're still cycling Matt... then I wouldn't panic too much at the moment.. the pH will come down once the system cycles, and further as it matures...

When you say one of the beds has "16mm screenings"... what exactly is it???

You may find over time that 16mm might be a bit too small/fine to handle a heavy feed load as your fish get bigger...

[RupertofOZ]

Oh... and I don't know how big your goldies are... but if you've got a dozen of them in a 500L tank... you're not going to have much room for many Silver Perch...

[Tsaphah]

Hi Matt,

First, welcome to a very addictive "hobby"! I have been having a similar problem with high pH due to the gravel I am using is a basalt rock which is high in Calcium Oxide. Tap water here can vary from 8.2 to 8.8! I add pool acid to drop it down (was adding a little every 12 hours a few weeks ago to keep it below 8), and also in my top up tank while its de-chlorinating, I get it down to 6.5 befor adding it. My system has been running for 2 months now and it is slowly (and I mean slow, we need patience with this) dropping, has held at 7.5 for the past few days :) . The high pH has been affecting the growth of my plants too, which has also been frustrating! Just don't give up!

Andrew

[MattG]

thanks for input guys. goldies are about 40mm , im not real fussed about them at the moment. Will re locate them to sump tank or aquarium later, they were just easy to obtain and cheap poo machines, while i make sure everything working ok! I did realize bit to late that i made a blue with gravel. I will try to get away with it for a little while, but eyes are open. i was also thinking around 30 silver perch? I have about 400 lt in fish tank and 300 lt in sump

[Aussie AP]

Hi Matt, too many silvers for that small tank I think. Start with half that.
Probably the blue metal buffering your pH. This is not a bad thing.
It will negate the effect of a falling pH which is what happens in a normal system with pH neutral grow media.
I believe scoria etc also adds minerals and bits and pieces to the system, ultimately good for plants and fish.
Over time the system will drop slowly, but at pH 8 you will get some nutrient lockout.
Cabbages and brocc will grow well but show nutrient deficiencies at that pH.
Cabbage especially, prefers a neutral to more acidic growing environment.
Look, you can adjust it with lemon juice etc, or once cycled, get your silvers and let their normal daily activities
drag pH down over time.
It's not a deal breaker and hey, you won't have to buy stuff to buffer pH.

[MattG]

thanks Darren