Backyard Aquaponics
A place to discuss aquaponics

I'm not sure if this is what Ichthyophthirius multifiliis looks like...but some of the trout have developed a lot of white spots




Close up they appear to be small lumps



The fish seem to be behaving normally, I havent seen any rubbing against the walls or floor yet. I'm at ~950ppm of salt now, perhaps I need to tip in some more, or are they stuffed?

Raise the salt level to a minimum of 3ppt...

I added 9kG of salt between midnight and 1am this morning mostly into the ST, and I rearranged the plumbing to return 3/4 of the water from the GBs directly to the ST. I left some going back to the FT (which SLOs into the ST) as I didn't manage to catch all the fish- 60 of them are now in the ST, where the salinity is about 3.3ppt, after adding another 3kg of salt to the whole system this morning. When it evens out it should be 3ppt everywhere, but I thought I might hit the ST with a bit higher concentration to start with... now I need to go into town and grab a proper net to catch the rest of the fish to put into the ST, as my small hastily constructed net in the middle of the night using some fencing wire and a small cloth bag isn't up to the task.

Given the Ich appeared just over a week after I received them, and there are no other fish in the system, would I be correct in assuming they were already infected? I read that Ich infected fish don't eat much... my 80 trout have only been actually eating about 5-10g of 3mm pellets per day, not showing much enthusiasm after the first day or so. A few eat some, but most have been ignoring the pellets.

The water has been in the 7.5-8.5C range the past few days, so I guess I'll need to keep the salt levels up for a month or more? At the moment I have chard, peas, brassicas, celery, beetroot, various onions and garlic planted, what sort of salt levels can they handle and still grow well? The large strawberry tower I've started constructing out of some big ceramic pots can probably go on the backburner for now...

Parasites and pathogens are always present in the water... and air...

Ick does often travel in with new fish (Why quarantine when getting new fish is a good idea if you have a system with other healthy fish already in it.) Yea the salt will take a while against Ick at those temperatures if that is indeed what it is. Chard and Celery will just taste saltier but I expect most of what you listed will be fine at 3ppt. Yea, strawberries don't like salt.

Other diseases are often present everywhere and only tend to show up when fish are stressed or water quality is poor. I once had some fish start looking like they had bumps almost like that before but they were fish I'd had for months. As far as I know, I've never had any Ick in my systems. I have had culmnaris outbreaks though and the cure for those seems to be, remove any fish far enough gone to be really easy to net without disrupting the rest, salt to an appropriate level for your species of fish (I have channel catfish so they can't take much salt so 3 ppt is about the max I would ever salt for a serious outbreak) and keep the water quality as perfect as possible and the stress as minimal as possible. Often those outbreaks seem to happen due to overfeeding especially at water temperatures between 65-79 F (18-26 C) Once the water is over 80 it doesn't seem as common for the channel catfish. I've also noticed that at least with the channel catfish, net injury is a common trigger for an infection. I noticed that if we netted fish out more than one day a week, it was common to have a dead fish the next week. Since I implemented the rule of only harvest once per week and NO netting catfish for show and tell, random infections leading to dead fish are very rare now here. Now I have absolutely no experience with Trout since it gets way too hot here so Hopefully some one who knows trout can say what those bumps really are likely to be.

good Luck

Salinity throughout the system is now 3.05ppt. I was away yesterday afternoon, so they didn't get fed, but this morning they cleaned up 10g of food pretty quickly, and then another 5g shortly afterwards, and it all went within a few minutes, so this is by far the best feeding I have seen with them.
The pH has been creeping up a bit this week, to 7.37 this morning, I reckon due to the fish not eating much, but now they have started eating well I think the pH may start to drop back down, as Ammonia production increases.
Water temp 8.8C this morning.

sounds like a good sign.

Ok I enjoyed your thread so much tonight I will be so close to getting the sack cause I'm supposed to be here working! Oh well these sick people can wait...

Looks like we are experiencing the same deal with the trout. I know in my marine tank white spot always comes to say hello when water parameters aren't ideal, it is always around.

I will add my bag of salt tomorrow, wished I'd done it today.

Brassicas actually like salt and hence grow well in coastal areas.

A very scientific study, if I didn't have a whingy toddler clinging to my legs each time I tried to do research/water quality tests I'd be able to contribute! One day...

Any thoughts on using garden lime instead of the shell grit? I believe it us more slow release than the hydrated stuff and still fine enough to dissolve as needed.

PS would love to hear how your wax latent heat thingo goes. I ran a similar experiment when designing a blood transport system using coconut oil. It had a great temp conversion , we needed 20-24•C but didn't hold enough heat. I wanted to try wax combinations but was getting too scientific for executive so they outsourced if and made it a multi million dollar project which in the end used ice, water ballast (my original design) and an expensive data logger in every shipment. Good old tax payers money. Not that I'm bitter or anything...

The shell grit I put in first didn't seem to have any effect at all, which is why I went to the Ca(OH)2 (I've got many 20kG bags of it here- for plastering the strawbale chook house), as I wanted to get to a bit above pH7 in a hurry before the fish were due, which worked well, though I would not try such drastic adjustments with fish in the tank. My tank water has become very clear in recent days, now I have sump tank and FT covered over, and I can see that what I thought might be a bit of Ca(OH)2 remaining on the bottom, amongst the brown algae is actually shell grit, so it is now doing all the buffering, and there is quite a lot of it in both tanks and spread through the GBs too. However, as I suspected it might, the pH has started to drop again now the fish are feeling a bit better, so the shell grit alone probably wont be sufficient to keep the water near neutral. The water was down to pH 7.13 in the FT this morning, so I'll be testing out (carefully!) the results of KOH additions within a day or 2 I think. I've got 5litres of 50% solution here.

Garden lime, mainly CaCO3, also has varying amounts of Calcium Oxide, and Magnesium Oxide and Carbonate, and should be ok I think, but I have no experience using it in AP. I think it is also of rather low solubility in water. I figure I have enough Ca in my system for now, and will go with the KOH for a bit. I did think about using KHCO3 as found in Eco Rose fungicide, which we have plenty of here, but that only makes up 94% of it. I phoned the manufacturer to discover what the other 6% is, and was told it was all surfactants, ie detergents, which you dont really want in your FT, although Charlie (Mod) said he has used it in the past

I've been adding a small amount of heat on sunny days with the buried pipes and ~20m of poly out on the ground as a heat collector, but the sun on the GBs is no doubt having a similar or greater effect due to a larger surface area ATM. Some heat is being added to the soil surrounding the FT by this, and this should help with moderating the temperature decline overnight. No rush on setting up the hydronics to get some serous heat into it yet, as I am not trying to grow Barra this season. I'll probably add the cooling system first to see how long I can extend the trout growing season into summer.

One test I did was to see if running the pump all night would have any obvious effect on the overnight temperature decline, as cold air is drawn into the GB and cools the media during water drains. I can't see any significant difference, on the night of 18/6 (3rd temperature dip, around 4000 on the graph). The other nights it was mostly 15on/45off overnight, and days are 40on/20off, although there was an occasional period of 3 hours straight pumping at various times of the day and a couple of evenings.
Average air temperature for the week was 7.8C.

While this comment is a bit off the current focus of the thread - thanks for this post as it has just solved for me how I can re-arrange my plumbing to give better control of flow through my fish tank and grow beds. That is, separately pumping to FT/NFT (continuous) and to GB (can now be flexible) Thanks

Gunagulla thanks for this thread heaps to learn.
Early on you mentioned your heating method. I have just bought a small evacuated tube heater (8 short tubes to a 30L tank). The system I want to heat contains Jade perch and about 1500L water.
What advice can you give in hooking this up to my system?

I built my system so that it would be a 3 minute changeover to send the water back to the sump and bypass the FT if required. I've since put all the fish back in the FT and have all the GB water returning back there too.

Re the heating- it depends a bit on how you have it all arranged, but I would suggest wrapping some Pex-Al-Pex or similar tubing around your FT in a big coil with no overlaping, and then wrapping that in a lot of insulation- 2 layers of 50mm foil-backed insulwool or similar should do it. Of course, it will need to be weatherproof, as you dont want the insulation to be wet. If you can mount the evac tube HWS below the FT, then take the HWS tank top outlet upwards to the top of the coil of pipe around the FT, and have the lower end of the coil fall all the way back to the HWS tank, then it will thermosyphon, and you wont need a pump to heat your FT. You could either manually open a stainless steel ball valve (15mm, not too expensive from plumbing supplier or the big B shop), or use a small thermostatically controlled solenoid, which would require minimal electricity to operate.
Depending on what your FT is made of, it may be worth wrapping a thin sheet of galvanised steel around it, between tank and Pex-Al-Pex, to spread the heat more evenly and avoid hot spots.
However, that is quite a small hot water system, and unless you insulate your tank and GBs very well, I dont think it will contribute sufficient heat in cold weather, and additional electric heating may be required.

Thanks!
Early on you we're talking about using wax because it holds more heat. Is it a special wax and are there any risks involved?

Beeswax, soy wax (non GM!), parafin wax, palm wax (roundtable certified of course!) etc have melting points around 55-60C and are able to store a lot of heat due to a reasonably high latent heat of fusion around their mp. You need to be able to operate around the mp to take maximum advantage of that, and by doing so can store up to ~10X as much energy as could be stored in the same volume of water. However, the advantage decreases with a wider temperature range, and isn't really worth the effort with say a 40C or more operating temperature range.

They are all fairly inert substances, with no handling risks.

The aim would be to heat it to a bit above melting, say to 65C, and circulate water past/through it until it is all solidified at say 50-55C, in order to extract the heat and transfer it to your system water. It gives you a reasonably constant temperature source of heat energy, so you can be more confident of how it will heat your system water, rather than doing it with water of continually falling temperature as heat is extracted. That's less of an issue with a large tank than it is with a small one though.

You need a large contact surface area between water and wax to ensure fast heat transfer and no slowing down of transfer due to insulating blocks of solidified wax getting in the way as it cools. There are plenty of ways to go about that, but one I plan to try is having lots of lengths of 20mm diameter sealed copper pipes of wax (plus a little air for flotation) in the hot water storage tank- that keeps the wax isolated from the system water, and provides good surface area, and is reasonably inexpensive to set up.
Alternatively you could have car radiators full of wax sitting in the water tank- providing a huge surface area of good conducting copper.
Copper might worry some people. but it isnt connected in any way to the system water, so is safe to use.