Backyard Aquaponics
A place to discuss aquaponics

Where my FT is positioned it gets a few pine needles dropped into the water. The water testing of the system seems Ok but do you think this could cause any other issues?

When I went to pick up my tilapia Travis (Hughey of Barrelponics fame) told me to put an old onion bag filled with pinestraw in the FT to keep the pH around 6.8 .. It did work, but I think I need to add a little more, it came down slightly but was quite high to start.. he suggested adding a bale to an IBC, but I could only fit around 1/3 in the bag I had..

It seems like a fine idea, if you can keep it from floating around ..

Long term you will probably want to keep the pine needles out as it will bring the pH down faster....

dont pine needles inhibit plant growth ? or am I thinking of something else

I thought the same thing. Not much grows under a pine tree. I only have a new system, fish for around 1 month, but I am happy with the grow so far. As for PH I have been testing every couple of days and it has remained between 7 - 7.5.

Is low PH bad? At what level should I get worried.

Not sure all the ins/outs, but can answer a couple questions about pine needles..

Often nothing grows under pine trees for two reasons: One, the soil is very acidic and two the needles act well as mulch. Based on their acidity, I would guess pine needles are very good at buffering a system down. That alone helps prevent algal blooms etc... Not sure about tannins released. Guessing not toxic to fish and trust that Trav know what he is talking about! The dude is way bright with a lot of good stuff.

CB

Thanks for the info, looks like it shouldn't be a major problem for now.

What is considered a low PH? I have trout and the PH is around 7, if it gets low what is the best way to bring it up?

Cheers

Bringing pH up is easy, you just need a buffer and a little often goes a long way. Shells and shell grit usually buffers around 7.6 (that means it starts dissolving when the pH is lower than that and hence it will only buffer up to that pH and not higher.) Limestone can buffer higher which is why limestone and marble are not recommended as the gravel for media. But small amounts of garden lime can be used to buffer a system up too. Small amounts at a time as you don't want to change pH too fast and you don't want to over do it as most plants prefer the pH range a bit lower.

As to how low is too low, well that is debatable and depends on many things. Once your bio-filter bacteria are established, they are probably fairly accustomed to the pH they are in, drastic changes to that pH can hurt your bio-filter bacteria. Drastic changes in pH actually tend to hurt everything in an AP system, avoid bouncing your pH. Anyway, back to how low is too low. Simply as a matter of expediency I've personally decided that for my test kit, since it can't read below 6 that I should keep my system pH enough above 6 so that I can be sure of what the pH is. That makes me think the pH range between 6.5 and 7 would be perfect area to maintain as it is in a readable range of the standard API pH test kit. Now if you have a pH tester that is accurate in a lower range and you are raising fish that like the more acidic water, then perhaps a lower pH is great provided the bio-filter keeps working and all else is good.

There are cases where people start a system off and all is fine for several months and then all of a sudden the pH crashes and the bio-filter crashes and the ammonia spikes and fish start dieing. This I guess is caused by the bio-filter bacteria using up all the available carbon in their work. Once the buffer is gone from the system water, the pH will drop and if it drops too far too fast for the given bacteria that colonized the system, then it can crash. So, it is always good to test the pH regularly and if it is getting too low to be certain of the exact pH or if the ammonia starts climbing as the pH is dropping, time to buffer the system with something like shell grit or if it is dropping too fast, a quicker acting buffer might be needed in small amounts in the short term till the shell grit can hold things.

So, my opinion, if the pH is below 6.5, I would probably add shell grit a hand full at a time until the pH isn't dropping anymore or perhaps even until the pH comes up to 6.5.

Now the disclaimer. I've not had to worry about keeping my pH of my system up since I have shells in my grow beds as media. My pH in any of the systems with shells as media has never gotten below 7. Normally it doesn't get below 7.6 and my top up water doesn't help as it comes out between 8 and 8.4 depending on season. However, if I ever manage to build another system that I get different media for, I will avoid the shells and over time the bio-filter action of Aquaponics is quite able to bring my high pH well water down below 7 and I will have to have a buffer on hand to balance it.

As to the pine needles. Well I don't think a small amount would be a huge problem as such, however, I would recommend putting a shade cloth or netting cover over the tank that will help keep the pine needles out as well as keep fish in. Leaves and pine needles can clog pumps and plumbing and intake grates so it is best if you can keep the debris out. Also covers over tanks are a good idea to keep other pets and small children out of the tanks.

TCLynx thanks for the reply. I will continue to test over the next week or so and then at shell grit as you have suggested. I have a 50mm square mesh cover to keep out animals (dogs, cats & birds) but will also look at a shadecloth roof to shade the FT and keep out a few more of the needles.

Shade cloth also helps against algae. I was having issues with brown string algae all of a sudden after I switched out my sump tank and hadn't put a new cover over it yet and another tank I had lately added and within a few days of covering both those tanks with 75% sand colored shade cloth, the algae seems to have gone away. I wasn't really expecting just 75% shade cloth to really get rid of the algae (and it might not work on pea soup) but it seems to have worked against brown string algae.