Backyard Aquaponics
A place to discuss aquaponics

Hi there,

My syste is a IBC 800L FT with a 200L GB flood and drain. I've had it cycling for 2 months now and have added gold fish and a few plants. However the plants didn't grow, in fact most are dead now. I have only just got a water test kit and have a ph of 8.4 I've managed to keep it at 8 with some ph down. But every time I add some more now it drops initially and then comes back up to 8. I've added 3 lots of ph down now. My GB media is 2/3 perlite with gravel on top. I've done the vinegar test with the gravel and all seems good. There is a slight algae/slim on the surfaces of the FT. Any thoughts on why my ph is coming back up?

Thanks in advance.

FT,

Perlite supposedly has a natural pH of 7.0 - 7.5 so that is not likely the culprit. You may have to start systematically testing different parts of your system if there is not something obvious keeping your pH up.

How is the pH of your top-up water before it goes in?

What was in your IBC before your fish and how well was it cleaned ahead of time?

What are the rest of your water test numbers?

--
Sam

HI Sam,

The ph of my top up water is 8.4, but i haven't had to top up in a while and definitely not while i've been trying to lower the ph. The IBC was vegetable oil, and i pressure washed them with hot water and soap and rinsed them out a few times. I'll do the other test numbers this afternoon. Thanks again Sam.

(a) dont bother with the pH down - not a good thing to use and should not use with food products.

(b) it is likely that you source water could be hard or have a lot of calcium, carbonates, lime in it.
probably need to check the KH and GH you can get a similar API KH and GH test kit (try eBay).
(or if near to a town city some aquarium and pond places may be able to test for you)

if case the issue will be that your system has a lot of buffering.
so adding small amounts will simple cause a short delay before the pH rises again.

**if you don't have anything in system** you can treat with hydrochloric acid.
you would need to temporarily remove the fish first and be very careful when re-adding them back in.

muriatic acid is basically HCL in its 'organic' form - but basically same stuff.
HCL breaks down into low risk by products.

(c) treating the fish tank will not be possible once it is up and running.

* any water being added should be treated with muriatic acid (hydrocholoric acid - HCL)
*BEFORE* being added to system.
* if source water is an issue then you may have to switch to rainwater,
ideally captured from an acrylic or laserlite type roof (esp. not zincalume)

(d) you can run a system with higher pH but most of the plant feeding has to be foliar
and/or direct to grow beds with a watering can.

(e) I am not really sure about using perlite - it is inert but may not be a great media.

(f) may simply be that the goldfish did not provide sufficient nutrients. In newer systems you
often have to water plants with some seasol (low nitrates) or power feed (nitrogen + seasol).
But just enough to keep them going - not too much.

(g) "There is a slight algae/slim on the surfaces of the FT."
This is OK, most likely the bacteria and is normal (usually greenish colour).
Goldfish should keep on top of the algae - else add couple yabbies or chinese algae eater.
(never use algacide in an AP system).

all of the above are covered in various posts around the forum and over time you will come across them.
However there are a number of people that run systems with pH 7.8 to 8.4. Many long term members.
so it is not essential to get the pH down.

would be handy if you post some pictures as that may help suggest issues to people that can help you.
how to post pics > viewtopic.php?f=4&t=21754

as there are a number of NSW members here it would also be handy to tell us where you are in NSW.
[perhaps edit your profile location to town, state, country - do that in the User Control Panel > profile]

Thanks Darren, can't upload my photos as they are to big a pixel. Currently on the iPad once I'm back on the pc I'll put them up. I think it must be the hardness of my water as it is artisien bore water, calcium from it sticks to everything.

Last weekend I started a new IBC system next to my current one. And I have put hydrochloric acid in it as not fish or plants and I tested it this afternoon with ph of 7. So once it has cycled and going well I'll transfer my fish to it and restart my current system. I'll add some seasol to the current plants and see if they take off a bit. THey have all either gone backwards or died in the grow bed. My amonia, nitrate and nitrite levels all came back at 0ppm

whereabouts are you in NSW ?

good idea with the 2 systems.

while your nitrates are down you can afford to use Seasol PowerFeed.
This will help your bacteria as well - add it to the grow bed with a watering can.
It has urea so will go to nitrates via ammonia.

If nitrates or ammonia start to show switch back to normal seasol.
(which is low in nitrogen and phosphorous).

are you getting much/any precipitate from the HCL ?
If calcium dominates your water it will be some form of calcium chloride.