Backyard Aquaponics
A place to discuss aquaponics

No, root rot only becomes a problem if the growbed is left constantly flooded without water flow for days.

Myself, C1 and others have constantly flooded, constant flow beds, and no problems.

If algae and water quality are not problems, you can sverely cut back on water pumping requirements. My system at it's current low stocking density only needs about 6 hours of pumping a day. However when it was fully stocked with Trout, 24/7 pumping was still not enough.

Thanks OBO and TCL, will trial 15/30 and see how it goes over next two weeks before summer break. Have never timed drain rate but will and will wack in an extra drain hole if I need to. After all it is easy to make new stand pipes if it does not work. With current low stocking rate -16 barra, three big goldies and 3 big marron the pumping is not needed but seeing that I don't need to worry about power usage it can't hurt.

To an extent the need for pumping will be related to all those different things but you can only reduce the pumping so far before the water starts getting pretty nasty even if you only have one poor gold fish in a 5000 gallon tank, the gold fish is not the only source of pollution in the water. Water without enough circulation becomes a problem.

The rule of thumb when designing a system is generally to turn over the tank volume each hour (or within whatever fraction of an hour the pump will be on.) After a system is cycled and running well, people can adjust the timing and reduce pumping some while carefully watching water quality/fish behavior/plants/etc to know what the limits are for their system/fish load/etc. However, at the first sign of trouble, I usually suggest making sure the pumping is back up to the tank turn over each hour.

As to if algae is a problem, a small amount isn't usually a big deal. If you can't see your fish, that isn't so good just because you can't see what's going on with them and pea soup has the ability to use up most of the oxygen in a tank overnight so make sure there is supplemental air pumping into the fish tanks over night if algae is thick.

Now if the plants are suffering from lack of nutes, then the algae is probably using up what little you have. Your plants might thank you if you can black out the tanks for a week or two while upping the pumping to hopefully help clear the algae bloom quickly. The dieing algae getting sucked into the grow beds can provide nutrients to the plants as well as act as a deterrent to the next algae bloom.

This is all new for me, but mine pumps 4min to the hour, 2000Lt fish tanks compleltey flood all growbeds 1000litres in that time period, have had some pretty hot days on and off and the plants have not suffered with this cycle, I weekly check my readings and everything is down around the zero

simso,
So you are saying that you pump perhaps 400-600 liters of water per hour with a system that has a 2000 liter fish tank and only 1000 liters of grow bed. If all your readings are good and the fish are happy, then this is probably ok for your current stocking of the system. However if you were to have say 30 kg of fish living in that fish tank, you might start to have some water quality problems with such a minimal water turn over depending on the fish.

Thanks mate, yes my stocking density is low, maybe at the moment I have a grand total of 7kgs of fish, what is it exactly that I should keep an eye out for when the density increases,

Currently in that 4 minutes of pump time, I have about 30 litres go through the heated roof panel, say 600 as a guess through the garden beds becuase they fill in 3 minutes and then go through the siphon tube overflow for the last 1 minute, and about 300 litres is simply cycled around the pipe circuit to ensure I dont have to much pressure in my pipes, if I open the cycling valve up to much "basically pressure to return valve" the water moves so fast that not only does it fill from the top it starts to fill from the drain below

Simso, if you have siphons, why use a timer? One of the benefits of siphons is that you can do away with the need for timers and pump constantly.

Well I have 5500lts of water and 12000lph pump that at head would be 9000lph, I am currently on 1hr on 1hr off and water is clearing but this also due to the fact I have shaded my tank area as well, as we have more sunlight you will get more algae if your water is still, well this is based on my observations in tank and dams, Ideal conditions is turn water over once an hour, many people here use the 15/45 cycle which is fine if you have the pump capacity, 3000lt tank to a 12000lph pump would suit 15/45, it is more economical for me to run a 12000lph pump for an hour/hour cycle than run a 25000lph pump for 15/45 cycle, but full covering tank with a tarp will fix algae, it will also increase the water temp though if in full sun, not a problem for the barra and goldies, but marron won't go past 30c

Probably because I dont know any better, fish are all new to me, I openly admitted to everyone that I have never raised even a goldfish before, but hydroponics Ive been doing for many years

The syphons I have are the standard style overflow ones with the large screen supplied by BYAP, that being said havent lost a single fish yet so all is good at the moment

BYAP ones are flood and drain standpipes with two 6mm holes in the bottom of the standpipe for the drain cycle. Siphons have no holes at the bottom (usually although mine ones at home do to facilitate constant flow to my NFT channel) and use a bell over the top of the standpipe to create a siphon when the bed fill and this empties the bed at a faster rate than the water is being pumped into the bed. This allows for constant pumping and no timer.

If you are using BYAP GB's with BYAP style drain standpipes I would change your pumping cycle over to 15/45 as a minimum. I did not quite understand your post regarding why you use 4min pumping times but if there is no real reason ie your sump and sump pump can handle the inflow from you FT pump when the beds start to overflow via the standpipe rather than drain via the 6mm holes I would change to 15 min.

Cool stand pipes not syphons, learned something today already.

Regarding pumping, not mine but in general. if the pumps fill a grow bed in say 5 minutes whats the point of continuing flowing for 15 minutes, wouldnt the water being pumped in the next 10 minutes simply go straight back out via the standpipes overflow, this to me would be pointless, as the volume below the stanpipe is slowly draining then anything added would simply run off and in effect do nothing or if it did do anything it would be quite trivial in the grand scheme of things. I was under the belief that 15 on 45 off was really becuase of the mechaincal timer limitations

The water pumped in when the bed is full still flows through the media. I believe that in your case, changing pumping from 4-15 minutes would give you around 3 times the solids removal from your tank and also 3 times the aeration via pumping. The water may pass through the bed to quickly to have ammonia converted down to nitrites, or nitrites to nitrates but there is definitly a solids removal benefit which will help water clarity. Joel or Faye could probably confirm this but I think most BYAP systems will be overflowing for a fair period of the 15 minute pumping time, I know our school beds fill in around half the time.

This is one of the main reasons I started this thread as I only just thought about the fact that I am not turning the entire FT volume over hourly at school and as so am likely to not be maximising solids removal via mechanical filtration through the GB media.

Well yes to the growbed, the additional 10 minutes of flowing is not necessary, however to the fishes in the tank... it is... hence the discussion on water turnover, the additional 10 minutes assist in providing the general recommendation of "one entire water changeover every hour"... You are also right that the 15/45 is a timer limitation...

Hence if within 5 minutes of pumping, you can push an entire volume of fish tank water through the growbeds once... then it would be alright...

Well I think water turnover all comes down to preferences of the owner, IMO I rather not mess around with the system to change water turnover based on stocking levels, even though the "once every hour" recommendation is based on maximum stocking levels. If I am stocked low, I still maintain the once every hour wherever possible, except when additional pumping will affect temperature hence affecting the fishes...

IMO, the additional pumping cost very little electricity compared to the additional expense when "shit hits the fan"... furthermore the additional pumping to meet the once every hour recommendation provides more aeration... and it takes one additional variable out of the equation when you are trying to find out what's wrong...

Okay, yes I agree 15 minutes of pumping compared to 5 minutes of pumping would definetly remove more solids using the same pump, but the same could not be said when comparing pumps against pumps minute for minute, my current pumps move more solids of the bottom in 4 minutes then the original ones I had in 15 minutes, I used to have crap all over the bottom all the time before I upgraded my pumps, now I barely have anything, to the point both tanks are crystal clean

Dont get me wrong, Im not trying to argue with folks, as I openly admit I have no idea, but the more I understand why people do what they do the more I can come to making my own informed decisions, and the easier it is to diagnose my own mistakes. Heres a couple of todays photos of the tanks in there greenhouse enviroment