Backyard Aquaponics
A place to discuss aquaponics

guys,
added 50 trout to a 300l GB, 700L tanks system 24 hours ago. system was cycled about a week earlier with good levels via hummonia
last weeks reading were constant thru out week via a pee in it once every 3 - 4 days (see below)

Am- .25
rites- 0
rates 40
PH - 7.0

Trout are between 4-5 inches. I've only planned to keep them in [/url]this system for no longer than 4 weeks,
Anyhow today my PH dropped down to 6.0 in 48 hours
Am - .25
rites - .25
rates - 10
PH - 6.0
Water temp 10 - 12 degrees

I guess my question is how low can the PH go till trout start to go belly up??
I've only thrown about 15 - 20, 5mm pellets in today to see if they were interested, but removed about 5, 3 hours later that werefloating on the surface. I've added some crushed egg shells and I'll probably get some shell grit tonight.
Also forgot to mentioned that I salted 1ppm today. trout seem to hide in the furthermost corner of the tank, but if I sneak up on them they are swimming all around, I think thats normal for the first week?

Regards
Matt

My pH is just over 6 and when the new trout went in was that low it wouldn't read, I originally thought the pH was the cause of my woes when first lot of trout died, turned out to be dead yabbies poisoning the water, don't try and bring pH up quickly as this will cause fish more stress, I think EB has fish at 5-6pH and Troutman also doubted at the time low pH was the cause, get some shell grit and put some in a stocking or 2 or even an onion bag, pH will slowly go up and will at least buffer where it is now, don't try and bring it up overnight, the plants will suffer more than the fish with low pH

I am not sure about this myself, but can 4-5 inches size trout take 5mm pellets??

they probably can because they are such guts, personally at that size I'd go for about 3mm. Still with that many trout in there, best off keeping feed to an absolute minimum anyway..

mine are on 5mm, only because I ran out of 3mm, but they seem ok on them, it is easier to over feed them on 5mm though

they don't seem to be holding back
Tonight I threw in about 20 pellets and were all gone about 5 mins later.
Performed a water test again tonight and every thing is the same except for the PH. It was back up at 6.8
I know that there can be PH swings if you get an algae bloom but it doesn't look like i have any issues with algae. anyone know which way the PH swings from morning to afternoon??
can you say put an extra drop of test solution to get an incorrect reading???

Regards
Matt

In a normal pond pond pH changes throughout the day, starting at its lowest point in the morning and increasing throughout the daylight hours. Photosynthesis during the day increases pH, and plant respiration during the night decreases pH.
The pH will fluctuate under the influence of carbon dioxide and ammonia being broken down if there is insufficient buffer in the pond system to mop up the excess free hydrogen ions.

Ever tested your KH level? Pure rainwater?

I have stuffed up a test and got a result of 6, when ph was 8.5 really.

Hey matty, give your test tubes a good sterelise in boiling water periodically.
ive had strange reading occasionally and I'm putting it down to this. Ive noticed sometimes if I don't clean out my previous days tests (leaving the test solution in the test tube overnight) it gives some very strange PH results in the next test, sometimes exremely high sometimes extremely low.

Privatteer,
I use rain water in my system which comes of a tiled roof, and generally has a PH of 7.8.
Don't have a GH test kit. thinking that I may of stuffed up the test, will find out tomorrow.

went and measured some fish and come to the conclusion that the smallest fish would be 4 inches most are between 5 & 6 inches with the larger ones close to 7 inches. I got the fish from Buxton and the fella there said he had just weened them on to the 5mm pellets.

matt

If the pH is low in the early morning and high in the afternoon, algae could be affecting things.

I have also just put a lot of fish into a newly cycled system and the next morning the pH is lower. I have noticed that the heavier the load on the bio-filter, the lower the pH will try to go.

If using rain water, you definitely want to keep shell grit on hand for when the pH gets below 6.5.

If I threw in 20 pellets they would be gone in about 4 seconds. Maybe they're spooked by you, try throwing the feed from afar. At the moment I'm feeding 90gm of 3mm pellets to 120 trout, I throw it in in small handfulls until they've cleaned up each lot and would get through the full amount (say many hundreds of pellets) would be all over in under 2 minutes easy.

Also in relation to PH, remember it is a logrithmic scale. That means a PH of 6, is 10 times more acidic than a PH of 7. 10 times! (PH of 5, 100 times more acidic than 7 etc). That's why PH swings are very dangerous, so low PH might not be the killer, but a sudden PH swing can certainly kill fish.

Also 1 week of cycling isn't enough, there's no way you would have an established bacteria colony in that time, so keep an eye on your Ammonia and Nitrite daily. Test before you feed, if they go above .5 (on either) don't feed for that day. Do this for 3 weeks and you should be pretty safe. I find the less you 'play' with the water the better, exercise restraint on the feed in the early stages and you should be pretty safe. Good luck!

Thanks guys,
I'll keep an eye on it.
My system is defiantly cycled, and been cycled for a week or more, it was a system that was previously running and had bacteria in it already.
I wouldn't have any nitrates if it wasn't cycled, (well thats what I've learnt form all the AP gurus here)
thanks for the feed back and I'll keep a close eye on things and let you know hoe things turn out.

regards
Matt

50 x 4-5" trout ... in 700L, with 300L of growbed... is about three times what you should have...

You wont be able to feed much more than what you are anyway... your filtration will struggle just to keep up with the respiration of that many trout... let alone feed conversion...

Don't worry about getting a gH test kit... the fact that your pH dropped so quickly is evidence that your buffering capacity (carbonate hardness)... is near nil... and evidence of the acidification due to the ammonia conversion related to that many fish in that amount of water...

Hardness is not really an issue that we need to be concerned about... and the least of your problems..

Diurnal pH swings are algae related... and pertinent to algael bloom management in pond based aquaculture... but not anywhere near so in AP... especially as you haven't any algae anyway... as you shouldn't...

Shellgrit will buffer back... slowly... if you really feel the need to buffer your pH back a little quicker... use a level teaspoon of "slaked lime"...

Regardless.... aerate like crazy... add another two 300L growbeds immediately... or cut your fish stocks in half.... minimum...

And yes... always rinse your test bottles after EVERY test... shake your test bottles prior to EVERY test... and rinse your tubes with some test water (discard) prior to EVERY test..

Thanks Rupe,

Water tests today are as follows
Am - 0
rites- .25
rates- 20
PH - 6.8

May of been a dirty test tube or the wrong amount of drops

I'm normally pretty rigid in regards to washing them out before and after I test,
I plan to keep a close eye on the levels till I can get my new system up and running & if needed I can quickly hook up another pump and bed as they are in position ready for media to go in. Just got to wait for the moneys to come in over the next week or two, so that I can complete the system.
In regards to the stocking of fish to GB ratio. I was under the guide that 3KG of fish required 100 of GB? I was lead to believe that the 50 trout that I purchased were around 100g each, bringing it to 5KG, thinking that I have a few week up my sleeve before they reach 9 KG, I've purchased the fish Did I get the formula right??
Regards
Matt

Hey matty, I was going to say to you that your GB filtration was way too low for 50 trout but I knew someone with more acurate knowledge would point it out, thanks Rup, Thats another reason I am considering waiting till next season for trout. I want my system to be fully operational and even then I will only be stocking 20 or so trout as I already have 50 SP.
I will possibly make more progress on my system tomorrow and if so will consider taking you up on your offer of some trout. but maybe not for a week or so when I know the whole system is cylced and operational. still a lot more work to do! I could even trade you some SP.